In several families of spiders, but principally in those like the Clubionidae and Salticidae, which are terrestrial in habits, there are species which not only live amongst ants, but so closely resemble them in their shape, size, colour and actions that it requires a practised eye to distinguish the Arachnid from the insect.
The evidence of the exact equivalence of the segmentation and appendages of Limulus and Scorpio, and of a number of remarkable points of agreement in structure, was furnished by Ray Lankester in an article published in 1881 (" Limulus an Arachnid," Quart.
The various comparisons previously made between the structure of Limulus and the Eurypterines on the one hand, and that of a typical Arachnid, such as Scorpio, on the other, had been vitiated by erroneous notions as to the origin of the nerves supplying the anterior appendages of Limulus (which were finally removed by Alphonse Milne-Edwards in his beautiful memoir (6) on the structure of that animal), and secondly by the erroneous identification of the double sternal plates of Limulus, called " chilaria," by Owen, with a pair of appendages (7).
(From Lankester, "Limulus an Arachnid.) of adaptation to the changed physiological conditions of respiration, and not of morphological significance, since a pair of renal excretory tubes of this nature is found in certain Amphipod Crustacea (Talorchestia, &c.) which have abandoned a purely aquatic life.
The bi-ramose structure of the post-oral limbs, demonstrated by Beecher in the trilobite Triarthrus, is no more inconsistent with its claim to be a primitive Arachnid than is the foliaceous modification of the limbs in Phyllopods inconsistent with their relationship to the Arthrostracous Crustaceans such as Gammarus and Oniscus.
(From Lankester, "Limulus an Arachnid.") Remarks.
(From Lankester, " Limulus and Arachnid.") Galeodes has been made the means of a comparison between the structure of the Arachnida and Hexapod insects by Haeckel and other writers, and it was at one time suggested that there was a genetic affinity between the two groups - through Galeodes, or extinct forms similar to it.
Lankester, " Limulus an Arachnid," Quart.
Idem, "Limulus an Arachnid," Q.
Pp. 25-32, 1892; Thorell, " On an apparently new Arachnid belonging to the family Cryj'tostemmidae," Westv.
In recent times the term tarantula has been applied indiscriminately to many different kinds of large spiders in no way related to Lycosa tarantula; and to at least one Arachnid belonging to a distinct order.
In Queensland one of the largest local spiders, known as Holconia immanis, a member of the family Clubionidae, bears the name tarantula; and in Egypt it was a common practice of the British soldiers to put together scorpions and tarantulas, the latter in this instance being specimens of the large and formidable desert-haunting Arachnid, Galeodes lucasii, a member of the order Solifugae.