THE S TO MA TO POD A 



321 



a narrow " neck," which, except for the lateral wings of the carapace 

 projecting on either side, recalls the similarly formed "neck" of 

 Leudfer and of the Trachelifer-lajrv& of Jaxea. The anterior thoracic 

 somites are much abbreviated and crowded together. The first and 

 second are apparently not distinct from the carapace in the adult. 

 The third and fourth are at most represented dorsally by small 

 sclerites overlapped by the hinder part of the carapace. The 

 fifth and succeeding thoracic somites are complete, and movably 

 articulated. The abdominal somites often increase in width 

 posteriorly, and their horizontally extended pleural plates may 

 become greatly expanded in certain species. 



The telson (Fig. 188, t) is very broad and its posterior margin 

 is generally cut into sharp teeth ; it is firmly united to the preced- 

 ing somite in certain species of Gonodactylus (Protosquilla, Brooks). 



Fn:. 188. 



Caudal fan of Squilla mantis, upper surface, en, endopodite ; ex, exopodite ; 

 j), process from peduncle of uropod ; t, telson, 



The surface of the carapace and of the body-somites is often 

 ornamented with longitudinal keels, and the telson is always more 

 or less elaborately sculptured. 



Appendages. The antennules (Fig. 187, a) have an elongated 

 peduncle of three segments, which bears three comparatively short 

 flagella. Of these, the two on the outer side spring from a 

 common stalk which is unsegmented ; the inner flagellum is also 

 unsegmented for a short distance from its base. 



The antennae (Fig. 187, a") have a protopodite of two segments, 

 a large exopodite, and a comparatively feeble endopodite. The 

 exopodite consists of a small basal segment and an oval mem- 

 branous scale (sc) with setose margins ; the endopodite has two 

 elongated proximal segments and a short flagellum. 



The mandibles (Fig. 189, A) carry a slender palp of three 

 segments. The oral edge is crescentic and strongly serrate, its 

 two cornua corresponding respectively to the incisor and molar 

 processes of other Malacostraca. The proximal cornu projects 

 upwards into the cavity of the mouth. 



The maxillulae (Fig. 189, B) have two endites, the distal 



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