392 



PROCEEDINGS OF THE ACADEMY OF 



[1897. 



Fig. 1. Synidotea bicuspida 

 (Owen), xf 



There are a large number of speci- 

 mens of this species in the collection 

 from Bering Sea and the Arctic Ocean. 

 The species is the largest and its shell 

 is the heaviest and strongest of any in 

 the geuus. This and the closely re- 

 lated Atlantic form, S. marmorata 

 Packard, and the small Californian 

 species S. consolidata (Stimpson), are 

 easily distinguished from any known 

 species by the triangular abdomen 

 with a comparatively sharp bicuspid 

 apex. Some of the largest specimens 

 measure 31 mm. in length and 14.5 in 

 width. 



Shallow water to 56 fathoms. 



Synidotea marmorata (Packard). Fig. 2. 



Idotsea marmorata Packard, Memoirs Boston Society of Natural History, 

 I, p. 296, pi. viii, fig. 6, 1867. Whiteaves, Canad. Nat., p. 262. 1875. 



Idotea 'marmorata equals I. bicuspida Streets and Kingsley, Bulletin Essex 

 Institute, IX, p. 108, 1877. 



? IdotJiea rugulosa Buehholz, Zweite Deutsche Nordpolarf., II, p. 285, 1874. 



Synidotea bimspida Harger, Proceedings U. S. National Museum, II, p. 

 160, 1879; also U. S. Fish Commission Keport for 1878, p. 352, 1880. 



Edotia bicuspida Miers, Jour. Linn. Soc. Loud., XVI, p. 06, 1SS3 (pars). 



This species was described by A. 

 S. Packard, Jr., in his paper on the 

 " Recent Invertebrate Fauna of La- 

 brador " from specimens taken in 

 Kyuetarbuck Bay in seven fathoms 

 on a sandy bottom. The National 

 Museum series consists of four spec- 

 imens from Station 2,431, lat. N. 

 43° 00' 00", Ion. W. 50° 47' 30", 

 129 fathoms; one from Station 

 2,436, lat. N. 43° 36' 00", Ion. W. 

 50° 06' 30", 36 fathoms, and five 

 from the Gloucester fishermen. 

 Compared with S. bicuspida it is 

 not so wide ; the thin epimeral pro- 

 jections so prominent in bicuspida 

 are much reduced in this species ; 

 the joints of the antenna? are relatively longer and more slender in 

 marmorata. The average size of the specimens of marmorata is much 



Fig. 2. Synidotea marmorata 

 Packard, x 2h. 



