n^n 



15 Fig. 1. Schematic structure of a hyperidd amphipod (male of the genus Hyperia). 



Ceph — head or cephalon; Pr — pereon or mesosoma; PI — pleon or metasoma; 

 Epi-iii — epimerons l-lll; Us — Urosoma; T — telson; A, — ^antenna I; An — antenna II; 

 Mxp — maxilliped; PpPvn — walking legs or pereopds I-VII; PI — natatory legs or pleopods; 

 Ui-Uiii — uropods I-IIl. 



of the genus Scina. Such a body shape is thus termed "scinoid". On the 

 other hand, in the Oxycephalidae the body is slender, elongated, and in 

 the Rhabdosoma, acuminate. 



The body is usually smooth, without longitudinal carinae; how- 

 ever, the posterodorsal margins of pereon somites V-VII and pleon 

 somites I-III are produced behind in somewhat prominent denticles (some 

 species of Lanceola, Scina, Parathemisto, Primno). Rarely, such denti- 

 cles are also present on pereon somites II-IV (Acanthoscina, Ctenoscina, 

 Spinoscina; in the latter genus these are very strongly developed, with 

 each exceeding the corresponding pereonite in length, and each with a 

 deeply denticulate anterior margin). Spiny processes on the body are also 

 very rare; only in the Spinoscina there are spinules on the pereon somites 

 and in Chuneola spinifera, one blunt spine in the lateral part of each of 

 the pereon somites II-IV. 



The shape of the head is highly variable. In the majority of surface 

 species it is large, spherical, higher than the pereon somites and the com- 

 pound eyes occupy almost the entire surface (Hyperia and related genera, 

 Pronoidae, Lycaeidae, and others). Sometimes it is equally large but not 



