294 PROCEEDINGS OF THE ACADEMY OF [Mch., 



ANEW SPECIES OF SEA-MOUSE (APHRODITA HASTATA) FROM EASTERN 



MASSACHUSETTS. 



BY J. PERCY MOORE. 



The common European sea-mouse (Aphrodita aculeata) has been so 

 frequently and so widely reported from the American Atlantic coast, 

 while none of the writers on our annelids have reported any other 

 species, that the identity of the species occurring on the two sides of 

 the Atlantic has been taken as established. It was, therefore, with 

 genuine surprise that I found, while prejmring a description from 

 Wood's Hole specimens for a report on the annelids of that region, 

 certain obvious points of difference between these and A. aculeata as 

 described by European writers. Since returning to Philadelphia a 

 more thorough examination of the literature and a detailed comparison 

 of specimens in the collection of this Academy with those belonging 

 to the U. S. F. C. laboratory at Wood's Hole, kindly sent to me by Mr. 

 Vinal Edwards, and two specimens of A. aculeata from the neighbor- 

 hood of Helgoland, for the opportunity of studying which I am indebted 

 to Dr. W. McM. Woodworth, of the Museum of Comparative Zoology, 

 have doubly convinced me of the wide distinction between the species 

 common in the deeper waters of the open sea off the Wood's Hole region 

 and the European species. This does not, of course, exclude the possi- 

 bility of the occurrence of the true A. aculeata also on our coast, yet 

 the few notes furnished by Prof. Verrill in his Report on the Inverte- 

 brates of Vineyard Sound lead to the belief that the species therein 

 recorded as A. aculeata is the one herein described, which it seems 

 probable is the onty one occurring south of Cape Cod.^ 



A. hastata is really less closely related to A. aculeata than to other 

 species of the genus and probably finds its nearest ally in A. japonica 

 Maren., which is widely distributed in the northern Pacific, From 

 that species it differs in having the notopodial setae free from the felt 

 and in the decidedly smaller number of neuropodial setae, which also 

 lack the terminal pilosit}^ in all of those examined. 



* Mr. James E. Benedict writes me that Prof. Verrill has informed him that 

 two species of Aphrodita are found on our coasts. Owing to the illness of Miss 

 Bush, to whom their discrimination is said to be due, I have been unable to 

 secure further information. 



