6 Addison E. Verrill, 



first four legs have a branchial plume or podobranchia on the 

 epipodial plate of the first joint, and also have arthrobranchiae ; 

 last four thoracic segments have pleurobranchiae. Thoracic legs 

 have but six functional joints ; none have chelae except the last 

 pair of the female. No pleopods on the first abdominal segment 

 in either sex. Telson and uropods have the distal part thin and 

 flexible, not spinose. 



The larvae are remarkable for their large size and thin, foliate 

 structure. They are of the form called Phyllosoma. Their entire 

 body is wide and exceedingly thin and transparent, in life, hardly 

 thicker than thin paper with long, slender bifid legs, all colorless 

 and transparent except the eyes, which are far apart on long stalks. 

 (See plates 3, 3 A.) 



They apparently live at the surface a long time in this form and 

 have several moults, changing gradually to forms more like the 

 adult. Such larvae were frequently taken by us in the Gulf Stream 

 and adjacent waters off our coasts, coming no doubt from much 

 further south. 



The most common kinds (plates 3, 3A, figs. i-3a) are supposed 

 to belong to Panulirus argus, but none were taken old enough to 

 prove this. Our figures represent three stages of this species (see 

 under P. argus}. Another quite different species (plate 3A, fig. 

 4) may belong to Scyllarus or one of the species of Scyllaridcs, 

 but its origin is very uncertain. This differs from the others in 

 having the large thin prethorax or head portion relatively longer, 

 and instead of being regularly elliptical or slightly oval its borders 

 are incurved in front of the middle, so that the anterior part is not 

 half as wide as the widest part ; the eye-stalks are longer, the eyes 

 rounder. The thorax proper is wider than in the other species and 

 its posterior incurvature or sinus is much wider and deeper; the 

 abdomen is bud-like with no segments developed in this stage, 

 though the legs are all fully developed and bifid, while in the other 

 species, with the abdomen in a similar state, the fifth pair of legs 

 can be seen only as minute rudiments (pi. 3, fig. i ; pi. 3A, fig. 

 2A). In this species (pi. 3A, fig. i) the third maxillipeds (mp'") 

 are shorter and not bifid as they are in the others. The other 

 mouth organs (m) are, however, more developed than in the 

 others, while the antennules and antennae (a', a") are less developed 

 and much shorter than in the youngest stage of the other species. 

 The latter will be described under P. argus, below. 



