536 EEPORT OFTIOMMISSIONER OF FISH AND FISHEEIES. 



legs are snbequal with the others and have styliforin dactyli. The 

 ischial and meral segments of the external maxillipeds are short and 

 broad. 



Another megalops, of which several specimens were taken in the 

 towing-net, in Vineyard Sound, August 5, has a remarkable, elongated 

 and tuberculated carapax. The carapax, including the rostrum, is 

 1.3™™ long and 0.84™™ broad, is armed above with several large 

 tubercles, and the posterior margin is arcuate and armed with a median 

 tubercular ijrominence. The front is somewhat excavated above and 

 expanded each side in front of the eyes, the anterior margin being trans- 

 verse, as seen from above, with a short and spiniform rostrum curved 

 obliquely downward. The chelipeds have slender hands and the am- 

 bulatory legs are long and slender, the posterior pair being subequal 

 with the others, and all having the dactyli styliforin. The abdominal 

 legs are very long. 



Several other forms of zoea and megalops were taken in Vineyard 

 Sound and vicinity, but, as they were not traced to the adult forms and 

 were none of them very abundant, they are not here described. 



SquiUa emjnisa passes through a remarkable metamorphosis, but none 

 of the earliest stages were observed. Specimens in one of the later 

 larval stages (Plate VIII, tig. 30) were taken at the surface in Vine- 

 yard Sound, August 11. These are nearly 6™™ long. The carapax is 

 proportionally much larger than in the adult, covering comptetely the 

 whole cephalothorax, has a long slender rostrum projecting far in front 

 of the eyes, and the lateral angles projecting backward in two slender 

 processes as long as the rostrum. There is also on each side, just behind 

 the eye, a small tooth on the margin of the carapax, and another similar 

 one on the posterior margin just beneath each of the j)osterior processes. 

 The eyes are very large and almost spherical. The autennulaj are short, 

 projecting scarcely beyond the eyes, and biramous, one of the ilagella 

 being short and unsegmented, the other longer and composed of three 

 segments. The antenmie are still without flagella, and the scale is 

 quite small. The first pair of legs (the appendages corresponding to 

 the first pair of maxillipeds in the Macroura, &c.) are well developed, 

 long, and slender, like those of the adult. The great claws are propor- 

 tionally largerthan in the adult, and have very much the same structure. 

 Of the six succeeding pairs of cephalothoracic legs, only the three ante- 

 rior, subcheliform ones are as yet developed, and these are quite small, 

 those of the third pair being smaller than the others, and projecting but 

 slightly beyond the carapax ; the three posterior, styliform legs are en- 

 tirely wanting, or represented only by slight sack-like protuberances. 

 The abdomen is not quite as long as the cephalothorax, including the ros- 

 trum and liosterioi? processes, and the five anterior segments are subequal 

 in length, smoothly rounded above, and furnished with well developed 

 swimming-legs, much like those of many macrouranas. The sixth seg- 

 ment is much shorter than the others, and has rudimentaiy appendages 



