172 C. Spence Bate on the Pencidea. 
Petalidium, n. gen. Four branchial plumes only, and four 
single foliaceous branchial plates. 
Acetes, Kdw. Like Sergestes ; fourth and fifth pairs of pereio- 
poda wanting. 
Eucormp, Dana. 
Eucopia, Dana. Gnathopoda developed as pereiopoda ; five 
anterior pairs subchelate ; two posterior ‘“ vergiform.” 
Chalaraspis, Willemoes-Suhm. Like Hucopia, but has only 
the posterior pair non-chelate. 
Sicyoniide, Kdwards. 
The genus Sicyonta has been clearly defined by M. Milne- 
Edwards, and illustrated by excellent figures of S. sculptus 
and S. carinatus in the ‘Annales des Sciences Naturelles’ 
for March 1830; but the general form of the animal and the 
texture of its external covering do not correspond with the 
character of Peneus in any single teature, except that the 
third pair of pereiopoda is chelate. Added to this, the bran- 
chies differ considerably in structure also. Although the 
structure is dendrobranchiate in form, it varies typically from 
that seen in Peneus and allied genera by having the ultimate 
rami foliaceous (flat and scale-like) instead of being cylindrical. 
These points (that is, the external appearance combined with 
the altered branchial condition), in my opinion, warrant the 
establishment of a distinct family for the true classification of 
the genus. 
Sicyonra, Edw. 
Sicyonta sculpta, Edw. 
Inhabits the Mediterranean, Milne-Edwards’s specimens 
having come from the Bay of Naples. That in the ‘ Chal- 
lenger’ collection was taken off St. Vincent, in the Cape-Verd 
Islands. 
Sicyonia carinata, Olivier, Edw. 
Is recorded by Milne-Edwards from the coast of Rio 
Janeiro. 
The ‘Challenger’ specimens were taken in shallow water 
at St. Thomas’s, in the West Indies. 
Sicyonia lancifer, Olivier, Edw. 
I have little doubt that this species is the same as S. cristata 
of De Haan (‘ Fauna Japonica,’ p. 190, pl. xliv. fig. 10). 
