Notes on North American Crustacea. 67 



Pinnotheres ostreum. 



Pinnotheres ostreum, Say; J. A. N. S., Philad. i. 67, pi. iv. ; f. 5. 



The female presents the following characters : — 



The meros-joint of the outer maxillipeds is naked and glossy, 

 broadly rounded and somewhat dilated at the inner angle ; and 

 the palpus is very short, with broad joints, with the exception 

 of the dactylus, which is extremely small and slender. The 

 ambulatory feet of the first pair are somewhat thickened, the 

 penult joint swollen at its extremity, and the dactylus very 

 short, almost conical ; those of the second pair are longer than 

 the others, with a dactylus two-thirds as long as the penult joint, 

 compressed and curved, almost ensiform ; the dactyli of the 

 posterior two pairs are compressed, but shorter and thicker 

 than in the second pair. In the chelipeds, the inside of the 

 fingers and part of the palm are pubescent. 



The male of this species is much smaller than the female, 

 and rarely found. I have seen but one, which was scarcely 

 one-eighth of an inch in length. The carapax is narrower, and 

 flatter above ; the front is more protruded, larger than in the 

 female, and separated from the rest of the carapax by a trans- 

 verse sulcus. 



The species is common in oysters from the coasts of the Vir- 

 ginian province. 



Pinnotheres maculattis. 



Pinnotheres maculatum, Say; Jour. A. N. S., Philad., i. 450. 



Carapax in the female narrowing anteriorly, the sides being obliquely 

 subtruncated ; median regions defined by deep sutures ; surface covered 

 with a dense but very short pubescence. Front prominent, deflexed, and 

 concave at its extremity. Meros-joint of the external maxillipeds rather 

 smaller, but thicker and stronger than is usual in the genus ; extremity of 

 the penult joint of the palpus pointed. Dactyli of first three pairs of am- 



