413 



the crustacean makes an about-turn inside the shelter and treading 

 with the pleopods reverses the course of its movement. Being weak 

 swimmers, the Phronima feed on less mobile zooplankton. Observing the 

 behavior of these crustaceans in the laboratry, laval (1968b) offered them 

 hydromedusae, ctenophorans, salpids, small pyrosomids, and pteropods 

 as food, which were readily consumed by them. On the other hand, 

 the stomachs of freshly caught phronimids of different species revealed 

 (Shih, 1969) the remains of crustaceans and even large diatoms, which 

 evidently shows that phronimids have a broad food spectrum. Generally, 

 336 having caught and held the prey by pereopods I-IV, the phronimid pulls it 

 inside the home and eats it there. If the prey is too large to pass through 

 the opening of the home, the phronimid holds it at the entrance and 

 consumes it there. The home itself can serve as a reserve store: during 

 food shortage in the surrounding environment, the crustacean intensively 

 eats the walls of the shelter and then abandons it. Observations have 

 shown that pereopods V, with such impressive subchelae, do not actively 

 participate in hunting and capture of prey; possibly they have a greater 

 role to play in defensive reactions of the crustaceans (Laval, 1968b). 



Shih (1969, 1971a, 1971b) and Laval (1968b, 1970) have provided 

 a revision of the family and together collected information on the distri- 

 bution and biology of individual species. 



The family includes two genera. 



KEY TO GENERA OF FAMILY PHRONIMIDAE 



1. Pereopods V with powerful subchela; 5th segment strongly broad- 

 ened and chitinized, with process on distal margin; 6th segment in 

 folded state touches distal margin of 5th segment and is also strongly 

 chitinized. Uropods II is both sexes only slightly smaller than rest of 



uropods 1. Phronima Latreille. 



— Pereopods V with weak subchela; 5th segment long, weakly broad- 

 ened, with denticles on anterior margin; 6th segment weakly chi- 

 tinized, when folded touches anterior margin of 5th. Uropods II in 

 males less than half as long and narrower than rest of uropods, in 



females reduced to very small unsegmented appendage 



2. Phronimella Claus. 



1 . Genus Phronima Latreille, 1 802 



Latreille, 1802: 38; Vosseler, 1901: 10; Shih, 1969: \-\00.—Bivonia 

 Cocco, 1832: 208. 



The head is large and dorsally bulged. All the pereon somites are 

 free. Somites I-II are very short and appreciably higher than the follow- 

 ing ones; somites III-V are the broadest (seen from above). Somite VI is 



