Three segments and the procephalic or prae-oral lobes.
His chief publications are: Cretan Pictographs and Prae-Phoenician Script (1896); Further Discoveries of Cretan and Aegean Script (1898); The Mycenaean Tree and Pillar Cult (1901); Scripta Minoa (1909 et seq.); and reports on the excavations at Knossos.
17), is the mouth or oral piece; the second, explained by the presence of a " latent endoderm-group " in those the antennal segment; the third, the intercalary or prae-mandibular invaginations.
42) the six somites of the mesosoma are not fused to form a carapace at an early stage, and they are followed by three separately marked metasomatic somites; the other three somites of the metasoma have disappeared in Limulus, but are represented (From Lankester, loc. cit.) by the unsegmented prae-anal region.
But although in such lower Crustacea the nerve-ganglia of the third prosthomere have not fused with the anterior nerve-mass, there is no question as to the prae-oral position of two appendage-bearing somites in addition to the ocular prosthomere.
They differ from the Crustacea in that they have only a single pair of prae-oral appendages, the second pair being definitely developed as mandibles.
The fact that the single pair of prae-oral appendages of trilobites, known only as yet in one genus, is in that particular case a pair of uni-ramose antennae - does not render the association of trilobites and Arachnids improbable.
Although the prae-oral pair of appendages in the higher Arachnida is usually chelate, it is not always so; in spiders it is not so; nor in many Acari.
- Euarthropoda having two prosthomeres (somites which have passed from a post-oral to a prae-oral position), the appendages of the first represented by eyes, of the second by solitary rams which are rarely antenniform, more usually chelate.
The Trilobites are known only as fossils, mostly Silurian and prae-Silurian; a few are found in Carboniferous and Permian strata.
A somite placed between the prosoma and mesosoma - the prae-genital somite - appears to have belonged originally to the prosomatic series (which with its ocular prosthomere and palpi FIG.
7) may be the tergum of the suppressed prae-genital somite.
- These start from highly developed and specialized aquatic branchiferous forms, exhibiting a prosoma with six pediform pairs of appendages, an intermediate prae-genital somite, a mesosoma of six somites bearing lamelliform pairs of appendages, and a metasoma of six somites devoid of appendages, and the last provided with a post-anal spine.
The prae-genital somite partially or wholly obliterated in the adult.
The prae-genital somite, after appearing in the embryo, either is obliterated (Scorpio, Galeodes, Opilio and others) or is retained as a reduced narrow region of the body, the " waist," between prosoma and mesosoma.
A prae-genital somite is often present either in a reduced condition forming a waist (Pedipalpi, Araneae, Palpigradi) or as a full-sized tergal plate (Pseudoscorpiones); in some it is entirely atrophied (Solifugae, Holosomata, and Rhynchostomi).
Pregen, The prae-genital somite.
A narrow prae-genital somite is present between opisthosoma and prosoma (figs.
- The possibility of another interpretation of the anterior somites of the mesosoma and the prae-genital somite must be borne in mind.
Excalation of one or of two anterior mesosomatic somites, besides the prae-genital somite, would then have to be supposed to have occurred also.
Prae-gen, Tergum of the praegenital somite.
A prae-gen opisth - 'II' opisth pa FIG.
Prae-gen, The prae-genital somite.
Between the bases of the sixth pair cf limbs and behind the prosomatic carapace is seen the tergite of the small prae-genital somite.
Opisthosoma when segmented showing the same number of somites as in the Pedipalpi; usually unsegmented, the prae-genital somite constricted to form the waist; the appendages of its 3rd and 4th somites retained as spinning mammillae.
Praegen, The prae-genital somite.
Opisthosoma consisting of only ten somites, which have no tergal and sternal elements, the prae-genital somite contracted to form a " waist," as in the Pedipalpi; the last three narrowed to form a A B prae-1 2345 6789 io I I111I IV V VI gen Opisttaosoma Prosoma FIG.
C, Lateral view, I to VI, proprosternites; c, mesosternite; and d, metasternite of the somatic appendages; a,b,c, prosoma; f, ventral surface the three tergal plates of the of the prae-genital somite; prosoma; prae-gen, the prae g, sternite of the genital genital somite; 1 to 10, the somite (first opisthosomatic ten somites of the opisthosoma.
The prae-genital somite is suppressed.
Prae-genital somite is absent.
I, Sternite of the genital or first opisthosomatic somite; the prae-genital somite, though represented by a tergum, has no separate sternal plate.
Prae-gen, Prae-genital somite.
Prae-gen, Prae-genital somite.
The prae-genital somite wide, not constricted, with large tergal plate, but with its sternal plate small or inconspicuous.
Prae-gen, Tergite of the prae11, The minute eleventh somite; genital somite.
The similarity of the form of their appendages to those of the scorpions suggests that they are a degenerate group derived from the latter, but the large size of the prae-genital somite in them would indicate a connexion with forms preceding the scorpions.
Prae-genital somite suppressed.
Prae-Mexican Plateau region, Mexico.
Prae-Mexican culture (?
(From Hickson.) a, Prae-corneal epithelium.
Most remarkable is its resemblance to the adult form of the Wheel animalcules, or Rotifera, which retain the prae-oral ciliated band as their chief organ of locomotion and prehension throughout life.
Prae, before, monere, to advise or warn), an impression relating to a future event.
Prae-itor, " he who goes before," "a leader"), originally a military title, was in classical times the designation of the highest magistrates in the Latin towns.
As the scene which Homer depicts is prae-Dorian Greece; it is reasonable to call his language Achaean.
Praeda, booty, from prae and the root hed - seen in prehendere, prendere, to grasp), booty, spoil, plunder taken in war, by robbery, or other violent means; particularly the quarry, the animal killed for food by a carnivorous animal; a beast or bird of prey.
The Rotifera are characterized by the retention of what appears in Molluscs and Chaetopods as an embryonic organ, the velum or ciliated prae-oral girdle, as a locomotor and foodseizing apparatus, and by the reduction of the muscular parapodia to a rudimentary or non-existent condition in all present surviving forms except Pedalion.
2) the head consists of the first somite only; that somite is perforated by the mouth, and is provided with a prostomium or prae-oral lobe.
Milne-Edwards and Huxley had satisfied themselves with discussing and establishing, according to the data at their command, the number of somites in the Arthropod head, but had not considered the question of the nature of the prae-oral somites.
Lankester (2) was the first to suggest that (as is actually the fact in the Nauplius larva of the Crustacea) the prae-oral somites or prosthomeres and their appendages were ancestrally postoral, but have become prae-oral " by adaptational shifting of the oral aperture."
The structure of the head in Arthropods presents three profoundly separated grades of structure dependent upon the number of prosthomeres which have been assimilated by the prae-oral region.
The three prosthomeres or prae-oral somites of Crustacea due to the sinking back of the mouth one somite farther than in Arachnida are not clearly indicated by coelomic cavities in the embryo, but their existence is clearly established by the development and position of the appendages and by the neuromeres.
The rami may be flattened for swimming, when it is " a bi-ramose swimmeret," or both or only one may be filiform and finely annulate; this is the form often presented by the antennae of Crustacea, and rarely by prae-oral appendages in other Arthropods.
Usually it becomes atrophied, leaving the eye as a sessile organ upon the prae-oral region of the body FIG.
Without parapodial jaws; without the addition of originally post-oral somites to the prae-oral region, which is a simple prostomial lobe of the first somite; the first somite is perforated by the mouth and its parapodia are not modified as jaws.
According to older views the increase of the number of somites in front of the mouth would have been regarded as a case of intercalation by new somite-budding of new prae-oral somites in the series.
That the buccal gnathobasic parapodia (the mandibles) were in each of the three grades of prosthomerism only developed after the recession of the mouth and the addition of one, of two, or of three post-oral somites to the prae-oral region had taken place.
" As one goes through the poems, one is ever and anon face to face with a myth of the most childish and barbaric type," which " carries one back to prae-Aryan days."