LONG NAMES FOR SHORT LARVZE 221 
in the Huphausie, while on the contrary it is very frequent 
among the Penzeidee.’ 
Family 2.—Sergestide. 
The branchial system is impoverished or lost, the 
epipodal plates and podobranchial plumes, when present, 
being restricted to rudimentary structures on the second 
maxillipeds. The first pair of trunk-legs, and some- 
times the second, are simple, the chelz of the third are 
minute, the fourth and fifth pairs are feeble, rudimentary, 
or absent. 
The genera assigned to the family are Sergestes, Milne- 
Edwards, 1830 ; Acetes, Milne-Edwards, 1830 ; Petalidium, 
Sp. Bate, 1881; Sciacdris, Sp. Bate, 1881; and Lucifer, 
Vaughan Thompson, 1829, a pre-occupied name altered 
to Leucifer by Milne-Edwards in 1837. A very few re- 
marks must suffice on the discrimination of these genera. 
In Sergestes the last two pairs of trunk-legs are rudi- 
mentary, in Acetes the last but one is reduced and the last 
is wanting, in Leucifer both pairs are absent. In Sergestes 
the arthrobranchiz are wanting, in Petalidiwm they are 
found on the second and third maxillipeds and the first 
three pairs of trunk-legs. In Sergestes, Professor Smith 
remarks, the branchiz are compound phyllobranchia, 
while those of Penevs in the preceding family are com- 
pound trichobranchie. 
The larval forms of Sergestes have been partitioned into 
genera and species. The youngest form known is desig- 
nated Hlaphocaris by Dohrn (see Plate [X.); another, and 
presumably later form, is called Platysdcus by Bate ; this is 
followed by Acanthoséma, Claus, and that by Mastigipus 
of the same author. The species known as adults are 
very numerous, of very various sizes, from many differing 
localities, Sergestes atlanticus, Milne-Edwards, being found 
both in the Mediterranean and in the Atlantic from 
Greenland to the tropics. The account of the genus occu- 
pies eighty-eight quarto pages and seventeen plates of 
Spence Bate’s ‘ Report on the Challenger Macrura.’ It 
