Vf I. On the Amphipodus genera, Cerapfs, Unciola, and Lepi- 



DACTYLIS, DESCRIBED BY ThOMAS SaY. By S. I. SmITH. 



The genus Cerapus. 



Say's description of the stnictx^i-e and habits of his Cerapus tuhxi- 

 laris, thongh incomplete and, in regard to some of the structnral 

 details, incorrect, certainly indicates a remarkable amphipod A^ery 

 unlike any of the other species which have been referred to the 

 genns. Though described by Say in 1817 from specimens found 

 " amongst fuci on the sea beach at Egg-Harbor [New Jersey] in 

 considerable numbers," it seems to have remained unknown for more 

 than fifty years. It was searched for in vain at the original locality 

 by Professor Verrill and myself in April, 1871, but in June of the 

 same year I dredged a few specimens in Vineyard Sound. These 

 specimens were unfortunately all females, while Say's description and 

 figures were based on the male only, so that I did not feel entirely 

 certain of their identity with Say's species. In the Report on the 

 Invertebrate Animals of Vineyard Sound, I inserted the species 

 under Say's name, with a query, and, after briefly describing the 

 coloration and habits, remarked that, " in the structure of the caudal 

 appendages, our specimens are quite difierent from the species 

 usually referred to Cerapus^ but I have not thought best to make any 

 changes in the nomenclature of any of the species until the discovery 

 of the male shall make it certain whether our specimens belong 

 to the species described by Say." In 1874 a considerable mimber of 

 specimens were taken, in the towing-net, on the evenings of July 17th 

 and 21st, in Noank Harbor, Connecticut, by Professor Verrill, though 

 I was unable to discover a single specimen in the same locality a few 

 days later. Among these sj^ecimens collected by Professor Verrill, 

 there are fortunately an abundance of males which agree with 

 Say's description and figure and leave no doubt whatever that the 

 species is the same as Say's. The following description and 

 figures are taken from these specimens. 



The general form of the animal is like Ericthordus difformis but 

 much more slender, the body being broad, depressed, very slender, 

 and, in the male, tapering slightly and continuously from the head to 

 the telson. The head is shorter than the first and second segments 



