- Ventral view of the posterior carapace or meso-metasomatic (opisthosomatic) fusion of Limulus polyphemus.
The prosoma (so-called metaI' to V', First five opisthosomatic stoma).
7', Sixth opisthosomatic somite.
1, The sternum of the first opisthosomatic or genital somite covering the V "' genital aperture and the first pair of lung sacs.
In front of it the narrow waist is formed by the soft sternal area of the praegenital somite; 2, the sternite of the 2 second opisthosomatic somite covering the posterior pair of lung-sacs; and 4, the spinning appendages (limbs) of the opisthosoma; a, inner, b, outer ramus of the appendage; I I, sternite of the eleventh --
I and 2, Sternites of the first and second opisthosomatic somites.
3 and 4, Appendages of the third and fourth opisthosomatic somites, which are the spinning organs, and in this genus occupy their primitive position instead of migrating to the anal region as in other spiders.
5, Tergite of the fifth opisthosomatic somite.
I 1, Eleventh opisthosomatic somite; an, Anus.
Under side of the uplifted genital or first opisthosomatic somite of the female; g, genital aperture; p, pitted plate, probably a gland for the secretion of adhesive material for the eggs; 1, the edges of the lamellae of the lung-books of the first pair.
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.
S' and S",Opisthosomatic tracheal d, Second plate of the prosomaapertures.
Io, Tenth opisthosomatic somite.
1, First opisthosomatic sternite covering the genital aperture g.
2, Second opisthosomatic sternite covering the second pair of tracheal apertures sp I .
Io, The tenth opisthosomatic somite.
I, Sternite of the genital or first opisthosomatic somite; the prae-genital somite, though represented by a tergum, has no separate sternal plate.
I, Tergite of the genital or first opisthosomatic somite.
1, Genital or first opisthosomatic (Original.) The serrula or the movable digit free at its distal end, narrowed at the base; no external lamina on the immovable digit.
Opisthosoma confluent throughout its breadth with the prosoma, with the dorsal plate of which its anterior tergal plates are more or less fused; at most ten opisthosomatic somites traceable; the generative aperture thrust far forwards between the basal segments of the 6th appendages.
Respiratory organs tracheal, opening by a pair of stigmata situated immediately behind the basal segments of the 6th pair of appendages on what is probably the sternum of the 2nd opisthosomatic somite and also in some cases upon the 5th segment of the legs.