DEVELOPMENT, GELASIMUS AFTER HATCHING 491 



First zoeal stage of G. pugilator (figs. 1 and 2). These zoeae are 

 relatively small (length from head between the eyes to tip of 

 telson, 1 mm.). They swim by means of the first and second 

 maxillipeds, and, so far as was observed, swim in only one direc- 

 tion, upward and slightly forward. When at rest the maxilhpeds 

 are habitually carried in the position shown in figure 1. In 

 swimming, these are raised to the sides of the carapace and 

 driven downward. When not swimming, the larva is nearly 

 always actively writhing about, chiefly by lashing the abdomen. 

 The first and second maxillae beat regularly and rapidly in such 

 a way as to drive a current toward the mouth opening. 



The carapace is slightly flattened from side to side. It bears 

 the usual anterior and dorsal spines, but shows no traces of lat- 

 eral spines. The anterior spine rises from the anterior margin 

 of the carapace between the eyes and passes ventrally almost at 

 right angles to the long axis of the body. It is about 0.2 mm. 

 long, straight, smooth, and evenly tapering from a slightly swol- 

 len base. The dorsal spine arises in the mid-dorsal line posterior 

 to the eyes and just above the heart. It is shorter than the an- 

 terior spine and curved posteriorly. There are constantly pres- 

 ent a pair of setae which arise on each side of the carapace, an- 

 terior and lateral to the base of the dorsal spine. The lateral 

 ventral borders of the carapace show the usual anterior and 

 posterior lobes. 



The eyes are sessile and immovable. The facets are clearly 

 indicated, but are not perfectly marked on the surface. The an- 

 tennule (fig. 20) is 0.07 mm. long and conical. From its tip arise 

 two or three long olfactory hairs and one or two short, sharp- 

 pointed setae. The antenna (fig. 28) is 0.11 mm. long and biseg- 

 mented. The proximal part of the basal segment is thick and 

 cylindrical. At its distal end its inner half is produced into a 

 stout serrated spine about twice as long as the proximal portion. 

 The outer half of the tip of the basal portion bears the distal 

 segment, which is small and cylindrical. From its tip arise two 

 setae, one long, which seems to be a continuation of the segment, 

 and a short outer one. 



