C. Spence Bate on the Penwidea. 193 
loped on the type of the Phylobranchiata. On this point also 
the figures of Michael Sars are insufficient; and he says 
nothing about the branchie in his ‘ Bidrag til kundskab om 
Christiania-Fjordens Fauna,’ 1868. 
Sergestide. 
The genera in this family yet require more extended re- 
search and observation. The specimens in the ‘ Challenger’ 
collection are numerous, but, coming mostly from deep water, 
are in a very injured condition. The first pair of pereiopoda 
is not chelate; but the succeeding two pairs are, and the 
fourth and fifth are simple. 
Genus SERGESTES, Edwards. 
Has the fifth pair of pereiopoda smaller than the fourth, 
a small leaf-like plate attached to three somites, and the 
branchiee arranged as follows :— 
Pleurobranchiz .......... Liga Loar en La Lian) 
Arthrobranchia .......... Ree Nee. ores ene 
Podobranchia ............ : 
Mastibranchia ............ 1 
Sergestes Kréyert, nu. sp. 
Like S. Frist of Kréyer, but is about 3 inches long; it is 
a female, and has the cervical fossa well defined on the dorsal 
surface. Rostrum a small anteriorly directed crest-like tooth. 
Ophthalmopod half the length of the first joint of the first pair 
of antenne, large, orbicular. First pair of pleopoda long 
and unbranched, fifth pair short and biramose. Telson as long 
as the inner plate of the rhipidura. 
Length 24 inches. 
Taken off Kermadec Island in about 500 fathoms of water. 
This species has two well-developed pleurobranchie attached 
to the penultimate somite of the pereion, two to the ante- 
penultimate, one plume and a leaf-lke plate to the next three 
somites, and one plume and a rudimentary mastibranchial 
plate to the first pair of gnathopoda. 
Sergestes prehensilis, n. sp. 
Like the preceding, but has no cervical fossa, and has the 
rostral crest larger and more sharp. ‘The first pair of pereio- 
poda is shorter than the succeeding, and has an organ for 
grasping at the last articulation between the ultimate and 
penultimate joints, such as Kroyer shows to exist in S. Hd- 
