2 U.S. NATIONAL MUSEUM BULLETIN 278 



This work is based primarily on the collections of the Division of 

 Crustacea, Smithsonian Institution. Extensive unidentified collections 

 were obtained from the National Museum of Canada, Woods Hole 

 Marine Biological Laboratory, University of Cape Town, Zoologische 

 Laboratorium in Utrecht, Duke University Marine Laboratory, and 

 the Smithsonian Oceanographic Sorting Center. In addition, I was 

 able to spend 4 months collecting along the Gulf of Mexico and south- 

 eastern Atlantic coasts of the United States. Through the cooperation 

 of the U.S. Coast Guard, I was allowed to accompany the USCGC 

 Madrona (buoy tender) on a cruise servicing buoys along the Virginia 

 and North Carohna coasts. These buoys yielded large numbers of 

 several species which aided in the study of intraspecific variation. 



Taxonomic Section 

 Taxonomic Characters 



Mayer (1882, 1890, 1903) usually used 11 characters to dehneate 

 caprelHd genera. These were the number of articles in the flagellum of 

 antenna 2, the presence or absence of swimming setae on antenna 2, 

 the number of articles in the mandibular palp and the setal formula for 

 the terminal article, the number of gill pairs, the number of appendage 

 pairs of both the male and female abdomens, the number of articles 

 in pereopods 3-5, the number of gill pairs, and the length ratio of the 

 inner and outer lobes of the maxiUiped. Occasionally he resorted to 

 other characters such as the fusion of pereonites 6 and 7 in Meta- 

 protella and Orthoprotella. This paper adds the position of the insertion 

 of pereopod 5 and the presence or absence of a molar on the mandible. 



Body spination varies considerably Mdthin the same species and 

 its value as a specific character is questionable. In Aeginina longicornis 

 this variation is quite pronounced and has caused a considerable 

 proliferation of names for what appear to be only infrasubspecific 

 variants. Harrison (1940) found that body spination did not appear 

 on Pseudoprotella phasma before the 10 th instar, which lends support 

 to my opinion that body spination is a questionable specific character. 

 It should be noted that those species which are spinose are frequently 

 covered Avith large amounts of detritus. Body spination may, there- 

 fore, offer some protective advantage and could possibly be correlated 

 with predatory pressure. 



The peduncle of antenna 1 is a useful character for the deHneation 

 of some species. The presence of setules sometimes distinguishes males 

 of Caprella linearis (fig. 14b) from other related species. Inflation of the 

 peduncular articles is exhibited in several species and is quite useful 

 for the separation of Caprella andreae from other members of the 

 Caprella a^utifrons group. 



