186 
CRUSTACEA. 
Eyes well developed, red j feet filiform, telson entire, short. 
Erythrops. 
Eyes well developed, black j feet short, with long bristles, telson 
with stout spines Leptomysis. 
Eyes rudimentary, separate j feet stout, with terminal claw. 
Amhlyops. 
Eyes rudimentary, coalite j feet filiform, without terminal claw. 
Pseudomma. 
Marsupium formed by the basis of all the feet, and also of 2nd pair of 
maxillipeds j otoliths rudimentary JBoreo?nysis. 
Incisive lobes of 1st pair of maxillae 2 j feet stout, hairy, joints 3 & 4 
dilated, terminal joint setiform Mysideis, 
Molar lobes of mandibles rudimentary. 
Appendage of upper antennae in cf large j tarsi 8-jointed. 
Mysidopsis. 
Appendage of upper antennae in ^ rudimentary j feet very stout, tarsi 
2-jointed ) pleopods of ^ with a peculiar coiled appendage. 
Siriella. 
2. Only some pleopods of cf different from those of $ . 
Only 1st pair of pleopods equal in both sexes j the next in cf natatory, 
2-branched Parerythrops. 
The first 2 pairs of pleopods equal in both sexes ; the next two not na- 
tatory in <5, penultimate pair very long. 
The last pair of pleopods natatory, 2-branched j dorsal shield overlap- 
ping almost all segments of anterior part of body Ilemimysis. 
The last pair of pleopods rudimentary as in $ j dorsal shield small. 
Mysis. 
3. All pleopods equal in both sexes Mysidella. 
Erythropsj new name for the preoccupied Ne^natopus (Sars), comprising 
goesi=^ Mysis erythrophthalma (Goes), id. 1. c. p. 24, pi. 1 j serrata, p. 27, pi. 2. 
figs. 1-12 5 microphthalma = Nematopus microps (Sara, 1863), p. 30, pi. 2. 
figs. 13-19 j pygmcea^N. elegam (id., 1862), p. 33, pi. 2. figs. 20-28; and 
abyssorumf p. 36, pi. 5. figs. 1-12 : all formerly named by Sars, but now fully 
described and figured : coasts of Norway, the last in the Chris tiania-fjord, at 
160-230 fathoms. 
Parerythropsj g. n. P. ohesa (^Nematopus^ Sars, 1865), Drobak, near Chris- 
tiania, 60-60 fathoms : id. 1. c. pp. 40-47, pi. 3. 
Pseudomma. Eyes without pigment, crystalline lens, or other optic ele- 
ments, forming a semilunar lamina at the base of the antennie. P. roseum 
and affine (Sars, 1869), Lofoden Islands and Hardanger-fjord, at about 200 
fathoms, in company with spp. of Erythrops : id. 1. c. pp. 48-60, pi. 4, and 
pi. 6. figs. 13-22. 
Mysis moehiij sp. n., locality unknown, the appendages of the pleopods in 
the male minutely described by A, Dohrn, Z. wiss. Zool. xxi. pp. 359-363, 
pis. 27 & 28. figs. 11-22. 
Euphausia : development described by Metschnikoff, ibid. pp. 397-401, pi. 34 ; 
it is hatched from the egg as a Nauplioid larva, and the 3 pairs of feet behind 
the larval natatory feet make their appearance at the same moulting, contrary 
to the rule prevailing in the Branchiopods, Oopepods, and Cirripeds. 
