ART. 7. STUDIES ON LARVAE OF CRABS — HYMAN. 6 



actually secured by hatching. The spines and telson both differ 

 strikingly from those of the other known forms. 



CepJialothorax. — All of the spines of the carapace are present and 

 are well developed. The dorsal and rostral spines are very long, 

 measuring 0.6 mm. (fig. 19). The lateral spines are smaller, 0.35 mm. 

 (fig. 20). The relative lengths of the dorsal and lateral spines are 

 helpful in distinguishing this zoea from that of Dissodactylus mellitae. 

 In the latter the dorsal spine is smaller and the lateral spine larger 

 than in P. maculatus. 



Appendages. — These are typically brachyuran (figs. 21-27). The 

 antennae are quite small and consist of a single ramus. They are 

 larger, however, than those of any other known zoea of Pinnotheres. 



Abdomen.— The abdomen is cylindrical and very different from 

 those of other larvae of Pinnotheres. The telson is typically bicor- 

 nuate and carries the usual six spines along its posterior border 

 (fig. 28). This departure from the typical form of the Pinnotheres 

 larva was mentioned by Faxon in a footnote. He secured his infor- 

 mation from tracings sent to him by Smith. A telson corresponding 

 exactly with this form is figured by Fritz Miiller and assigned to a 

 Pinnotheres. 



DISSODACTYLUS MELLITAE Rathbun. 



This zoea is common enough in the tow at Beaufort. It is large 

 and robust, not suggesting the tiny adult crab. The zoea resembles 

 that of Pinnotheres maculatus rather closely but may be distinguished 

 by the dorsal protuberance on the first abdominal segment as well 

 as by the shorter dorsal spine (figs. 29 and 30). 



Cephalothorax. — -All of the carapace spines are present and are 

 well developed. The lateral spines especially are large and stout. 



Appendages.— Th&Ye is nothing peculiar about the appendages 

 (figs. 31-36). The antennae are minute and uniramous. The 

 sensory hair on the terminal segment of the endopodite of the first 

 maxilliped is plumose. 



Abdomen. — The abdomen resembles that of P. maculatus very 

 closely. The horns of the telson are almost parallel with each other 

 (fig. 37). 



PINNEXA CHAETOPTERANA Stimpson. 



The first zoea of this species has been described by Faxon and 

 by Smith. The following description is based on material taken at 

 Beaufort. The description corresponds with those formerly given. 

 Tlie pigmentation is given in the table on page 2. 



The zoea is distinguished by its comparatively small spines and, 

 especially, by the enlarged fifth abdominal segment and median 

 process of the telson. The transformation of the last zoea into a 

 megalops is given by Smith but he does not give description of either. 



