Genus Callinectes. 5G9 



curving first inwards from near the base for over two thirds 

 of their entire length, even so as to touch each other, and 

 then with a strong curve outwards to their termination. 

 Abdomen of the female almost circular in its outline, ex- 

 tremely broad, completely covering the sternum posteriorly, 

 its second segment being but little narrower than the oth- 

 ers. Chelipeds rather heavy. Meros with three stout spines 

 on its interior border, and one slightly developed one on 

 its external anterior angle. Carpus with two somewhat 

 granulated ridges, the outer one of which is sometimes 

 produced into a rather obtuse spine. Manus with a stout 

 spine at the point of its upper articulation with the carpus, 

 and a small one near its point of articulation with the 

 dactylus. The carpuses of the first three pairs of ambu- 

 latory feet have two very small spines on their upper side, 

 one of them, however, being sometimes almost obsolete. 

 The meros joint of the external maxillipeds is sharply 

 truncate at its anterior extremity, and its external angle 

 is rather sharp. 



Having had before me hundreds of specimens of this 

 species, I have been able carefully to study all of its vari- 

 ations or departures from the normal form, and some of 

 the changes that it undergoes in its growth. Though in 

 the adult the breadth of the carapax is twice its length, 

 the young are much narrower, — in small specimens, say 

 half an inch long, it is not more than one and a half times 

 as broad as long. The teeth of the antero-lateral border, 

 which in the adult are sharp, with concave sides, are in 

 the young broad and conical, with almost convex sides. 

 The chelipeds also increase in length with age. When 

 young, the intromittent organs are also very short, in spe- 

 cimens from one half to one inch in length, not more than 

 two thirds the length of the tail, and almost straight, grow- 

 ing longer and curving as they advance in age. The pe- 

 nult segment of the abdomen is not laterally concave, as it 



JOUliNAL 1!. S. N. H. 72 



