188 STALK-EYED CRUSTACEA. 
midway between the anterior margin and the cervical groove, at a rather 
higher level than the antennal spine, a lateral spine on the posterior edge 
of the cervical groove a little lower down than the antennal spine, and an- 
other (the branchiostegal spine) at the anterior end of the cervical groove, 
just behind the antero-lateral margin of the carapace. The antero-inferior 
angle of the carapace is not armed with a spine. The antennular flagella are 
missing ; the prosartema is somewhat longer and narrower than in P. dio- 
medee. The antennal scales are broad and foliaceous. The antennal flagella 
are more than twice the length of the body. The terminal segment of the 
mandibular palpi is elongated and much narrower than the preceding seg- 
ment, but neither segment is so narrow as in P. diomedew. The legs do not | 
differ in any important regard from those of P. diomedew save that the 
exopods attain a greater development ; on the second maxillipeds the exo- 
pods are equal in length to the meri, while on the succeeding pairs of 
appendages these organs, though small, assume macroscopic proportions even 
unto the posterior thoracic legs. The number and arrangement of the gills 
are expressed by the following table : — 
Somites {te Allis De xe XI sd05  S8the >any 
Pleurobranchie 0 0 i 1 1 1 il ao 
Arthrobranchie 0 2 2 2 2 2 2 0 = 12 
Podobranchiz 0 i 0 0 0 0 0 OF ae 
Epipods 1 Ie 1 1 1 1 1 ()— (7) 
19+ (7) 
It thus appears that the most important structural differences between 
P. diomedee and P. ocularis are these: the strong emphasis of the branchio- 
cardiac groove in the former species, together with the smaller size of the 
exopods of the maxillipeds and legs, the presence of a minute branchial 
plume on the seventh (first maxillipedal) somite, and the position of the 
lowest of the spines on the side of the carapace which in P. diomedee is 
marginal, but in P. oeularis lies a little way behind the margin. It does not 
seem to me that these differences are of sufficient weight to be esteemed of 
generic value. 
In all important structural characters, including the disposition of the 
gills, Peneopsis agrees with Haliporus. The latter genus may be conveniently 
retained, however, to include the soft-shelled species with long abdomen and 
long posterior legs. P/eoticus Bate * does not seem to be sufficiently distinct 
* Rep. Challenger Macrura, p. xii. = Phélonicus Bate, op. cit., p. 273 (nom. preoc.). 
