794 MR W. T. CALM AN ON 



where the same number of joints is attained in the posterior thoracic legs. Hansen, 

 indeed, regards the possession of eight joints in the thoracic legs as characteristic not only 

 of the Mysidse, but also of the Cumacea and Edriophthalmata, while in the Euphau- 

 siidse and Decapoda only seven joints are recognised. Anaspides further resembles the 

 Mysidse and the other groups above associated with them in having the legs flexed at 

 the articulation between the fifth and sixth joints instead of between the fourth and fifth 

 as is the case in the Euphausiidse and Decapoda. 



Abdominal Appendages. — The first five pairs of abdominal appendages have the 

 exopodite developed as a long, many-jointed flagellum fringed with setae, and forming 

 a powerful swimming organ. The endopodite of the third, fourth, and fifth pairs is a 

 small rounded lobe, two-jointed, but without any trace of appendix interna. The 

 endopodites of the first and second pairs are in the female similar to those of the suc- 

 ceeding pairs, but in the male they are considerably modified. In the first pair the 

 endopodite has the form of a thick lobe, curved inwards and hollowed on its anterior 

 face, and having near the distal end of its inner edge a rudimentary appendix interna 

 carrying a tuft of short " coupling hooks" or retinacula. In their natural position the 

 two endopodites of the first pair are turned horizontally forwards between the bases of 

 the last pair of thoracic legs ; they are united by the retinacula, and together constitute, 

 in consequence of their curved and hollowed form, a shallow trough in which the en- 

 dopodites of the second pair play. The latter are longer, two-jointed, the long first 

 joint carrying a bunch of retinacula and a few spines near the tip. These appendages 

 lie coupled together within the groove formed by the first pair of endopodites, and 

 between them and the sternal surface of the thorax. In short, these first and second 

 abdominal appendages occupy much the same mutual position in the male Anaspides 

 as they do in the male Crayfish. Among the Schizopods, the Euphausiidse alone agree 

 with Anaspides in the circumstance of the two anterior abdominal appendages being 

 modified in the male, but no very close comparison is possible between the structures 

 seen in Anaspides and the elaborate system of lobes, hooks, and stylets which differ- 

 entiate these organs in the Euphausiidse. 



The sixth pair of abdominal appendages or uropods form with the telson a tail-fan 

 of the characteristic podophthalmate form (Plate II. fig. 14). Both exopodite and 

 endopodite have a slight median keel, and the exopodite is crossed a little beyond 

 the middle of its length by a transverse suture which, starting from the outer edge, 

 reaches to within a short distance of the inner edge. 



The telson is less than half the length of the inner plates of the uropods, rounded at 

 the end, which is fringed with spines. 



SYSTEMATIC POSITION OF ANASPIDES. 



If we are content to deal with the generally recognised limits and definitions 

 of the Crustacean groups, and if we acknowledge the commonly but not uni- 



