184 A HISTORY OF RECENT CRUSTACEA 
on account of the contradictions in different writers in 
regard to the third maxillipeds of Callianassa, some call- 
ing them pediform, others operculiform. In Cheramus 
they are distinguished as pediform, but it seems rash to 
establish a new genus on the very character which some 
authors ascribe to the old one, especially as Callianassa is 
not unrepresented in England, France, and the Mediterra- 
nean, and specimens might have been examined to clear 
up the disputed point. In the British Museum Leach’s 
type-specimens of Callianassa subterranea, from Kings- 
bridge in South Devon (Salcombe at the mouth of the 
Kingsbridge estuary being probably intended), have third 
maxillipeds that might well be described as pediform. 
But other specimens at the same museum, which have 
been labelled as belonging to the same species, were 
shown me by Mr. Pocock, and in these, which came from 
Jersey, the third and fourth joints of the maxillipeds in 
question are greatly expanded, quite deserving the name 
operculiform. But these specimens also have a more 
quadrate telson than those from Devonshire, and are 
doubtless quite distinct. Since, however, in the type of 
Callianassa the maxillipeds are pediform, the chief reason 
for the institution of Cheramus is cut away. Its name 
signifies ‘a gap,’ but it has net succeeded in filling one. 
Callianidea, Milne-Edwards, 1837, closely resembles 
Callianassa, but with some differences in the branchial 
arrangements, and, besides having the second pleopods 
like the following three pairs, in all these pleopods ‘ the 
margins, instead of being fringed with small hairs or cilia, 
have these modified into soft and flexible articulated mem- 
branous filaments.’ Milne-Edwards supposed that these 
were true branchial appendages, and that a link was thus 
established between this family and the Squillide in the 
sub-order Stomatopoda. With his own genus he coupled 
Guérin’s sea. But Mr. Spence Bate regards it as pro- 
bable that Guérin’s genus was founded on a damaged 
specimen of Callianidea, and with some reason thinks that 
the fringed pleopods of that genus cannot be regarded as 
branchial for purposes of classification. 
