CH. Ill] SPECIES OF SEROLIS. 173 



it is made the type of a distinct family of that group, and 

 it is in many respects peculiar ; the outward form recalls 

 that of the extinct Trilobites — " An protypon Entomolo- 

 thi ? " asks Fabricius, and attempts to reinstate the genus 

 in the neighbourhood of those long defunct Arthropods 

 have lately been made. Apart from this spurious claim 

 to interest, Serolis has a genuine attractiveness by reason 

 of its remarkable geographical range. It may be ex- 

 plained in the first place that Serolis — or the Serolidse, if 

 the family be approved of — differs from all other Isopods 

 in the facts that (1) the first two segments of the thorax 

 are more or less completely united with the cephalic 

 shield, (2) that the last three segments of the abdomen 

 are fused with the telson, (3) the wide depressed body 

 with usually elongated epimera. This assemblage of 

 characteristics divides the Crustaceans in question from 

 others. 



There are in all twenty-six species of the genus, of 

 which perhaps some (those queried) are a little doubtful. 

 They are thus distributed : 



(1) Off Pernambuco (675 fathoms), Serolis gracilis 1 . 



(2) Off Pernambuco (410 fathoms), Serolis ant- 



arctica. The same species also found in 1375 

 and 1600 fathoms near Crozets. 



(3) Off Rio Janeiro in 600 and 2040 fathoms, Serolis 



necera. 



(4) Off antarctic continent, near New Zealand in 



410 — 1975 fathoms, Serolis bromleyana. 



1 For a full account of this genus see Beddard, Report Zool. Gliall. 

 Exp. Vol. xi., and Pfeffer, Jahrb. Hamb. wiss. Anstalt. 1888. 



