220 A HISTORY OF RECENT CRUSTACEA 
species of the deep-sea genera, such as Benthesicymus and 
Gennadas, Spence Bate, the eye-stalk sends out a promi- 
nently pointed tubercle, with a small circular lens at its 
extremity, served by a distinct branch of the optic nerve, 
this single lens being very translucent and without trace 
of pigment. Gennadas received its name, meaning ‘of a 
noble race,’ because it ‘approximates nearer than any 
other to the little crustacean named Penceus (Kola) spe- 
ciosus in Salter and Woodward’s map of fossil Crustacea.’ 
Peteiniira, Spence Bate, 1888, meaning ‘ flying-tail,’ is 
established for a single species Peteinura qubernata (see 
PlateIX.), founded on a single specimen an inch long, taken 
at the surface of the Atlantic at night time. There can 
be no doubt that the supposition is justified that the 
Specimen is an immature form. ‘There is a very long 
slender rostrum such as is common in larval forms, but 
the strangest peculiarity is at the other extremity of the 
animal. The sixth segment of the pleon, which is about 
as long as the four preceding segments together, carries a 
pair of uropods of which the inner branch is small and 
rudimentary, whereas the outer is nearly as large as the 
rest of the animal, a truly prodigious rudder! If ever 
the tail could wag the deg, one might expect a parallei 
to that phenomenon in this instance. 
Cerataspis, Gray, 1828, of which Cryptopus, Latreille, 
1829, is a synonym, has been lately shown to have ‘ almost 
all the characters of the typical Penzide.’ Gray referred 
his Cerataspis monstrosus to the ‘Fam. Nebaliadze (Les 
Schizopodes Latr.),’ but Giard and Bonnier say, ‘the 
antennules, the antenne are absolutely those of the 
Penzide ; the second maxilla possesses the four charac- 
teristic plates ; the endopod of the first maxilliped is five- 
jointed, the second maxilliped is geniculate, the third is 
transformed into a locomotive appendage; the thoracic 
legs are provided with long swimming branches (exopods) ; 
the first three pairs end in chelz ; the last two are simple, 
&c.’ Referring also to P. J. van Beneden’s discovery of 
the nauplian embryo, they remark that ‘ among the Schizo- 
pods the nauplian embryo has only as yet been observed 
