MAR'INB GAMMARIDEAN AMPHIPODA 465 



short coxae which generally do not touch each other, and degraded 

 mandibular molars. 



The Phliantidae differ from Talitroidea by their degraded man- 

 dibular molars and the general aspect of their depressed, massive, 

 often processiferous bodies with laterally splayed coxae. Phliantids* 

 never have enlarged male second gnathopods as do most talitroids, 

 especially marine ones. 



*See supplement. 



Classification of Talitroidea 



Bulycheva (1957) partitioned the Talitridae, emended and restricted 

 the concept of the Talitridae and removed several genera to two new 

 families, the Hyalidae and Hyalellidae. Morphologically there are 

 some small conflicts in her arrangement but they detract little from 

 what appears to be a sensible and logical arrangement, although the 

 classificatory criteria used are to a large extent not qualitative and 

 indeed to some extent are concerned with the ecology of the organisms. 



As so outlined, in her extensive paper, the Talitridae are confined 

 to entirely terrestrial genera, many species of which dwell on the 

 strand but nevertheless are not aquatic. The Hyalidae are exclusively 

 marine, being characterized by cleft telsons. The Hyalellidae inhabit 

 both marine and fresh waters, with more genera but few species in the 

 oceans than in freshwater, where one genus, Hyalella, has 27 species. 

 Morphologically, it is impossible strictly and qualitatively to separate 

 the terrestrial Talitridae from the concepts of the other two families. 

 Bulycheva (1957) in her figure 22 has given an excellent synopsis of 

 the telsons of the three families, showing Talitridae with generally 

 uncleft, heavily spinose telsons; Hyalidae with cleft, poorly spinose 

 telsons; and Hyalellidae with uncleft, poorly spinose telsons. She 

 shows the fluvial Chiltonia mihiwaka in the Hyalellidae with uncleft 

 telson but Hurley (1954a) shows it with partially cleft telson, al- 

 though other chiltonias may have the telson uncleft. Chiltonia is not 

 assignable to Talitridae because of the poorly spinose telson. Najna 

 shows both uncleft and minutely cleft telsons in the same species; 

 Bulycheva assigned the genus to the Hyalidae, but it should be 

 removed to a new family because of its mandibular molar. 



Figure 168. — Talitroidea: a, Talitrus saltator (Montagu) (Sars, 1895, pi. 9, as T. locusta) 



b, Hyale chevreuxi K. H. Barnard (Chevreux 1901a, as H. macrodactylus). Gnathopod 2 



c. Insula antennulella Kunkel (1910); d, Chiltonia mihiwaka (Chilton) (Hurley, 1954a) 

 e, Hyale bassargini Derjavin (Gurjanova, 1951); /, Talitrus; g, Allorchestes plumicornis 

 (Heller) (Gurjanova, 1951, as J. ptilocerus). Gnathopod 1: h, Talitrus; i, Insula. 



