CRUSTACEANS THAT ARE NOT CRUSTACEOUS 245 
margin that projects and lies beneath a corresponding 
process of the anterior margin of the first somite of the 
pleon, and bolts down the carapace so securely that it is 
difficult to elevate it.’ Some of the other genera show a 
falling off from this vigorous character, for Bentheocdris 
exuens, Spence Bate, from 2,357 fathoms in the South 
Pacific, ‘resembles many of the deep-sea forms in being 
soft and membranous,’ and both Hymenodira, Sars, 1876, 
and Meningodora, 8S. 1. Smith, 1882, alike signify ‘a mem- 
branous skin,’ the latter having for its type Meningodora 
mollis from the Atlantic, and the former having been 
instituted to receive Pasiphaé glacialis, Buchholz. 
In describing Hymenodora, Sars observes :---‘ With the 
genus Pasiphaé its chief agreement consists simply in the 
two foremost pairs of feet being furnished with chele, and 
in all of the pairs having a natatory branch (exopodite) ; 
but this branch is far more powerfully developed than in 
the former genus, where it has merely the appearance of a 
rudimentary appendix. Moreover, the two foremost pairs 
of legs are considerably smaller, whereas the three suc- 
ceeding pairs, which in Pasiphaé are small and feeble, 
exhibit a powerful development. From the genus Pasi- 
phaé it also differs by reason of its comparatively more 
thickset, almost rounded form of body, the unusually thin, 
membranaceous integuments, the rudimentary character 
of the eyes, the very different structure of the oral parts, 
and the peculiar form of the caudal appendages.’ He 
looks upon it as ‘marking in some respects a kind of 
transition to the Schizopod type,’ an admission which 
Spence Bate would appear to have overlooked, since he 
does not refer to it in support of his own view that the 
Schizopoda should be included among the Macrura. 
Spence Bate makes Meningodoru a synonym of Hymeno- 
dora, to which he adds several species, placing it, together 
with Notostiémus, A. Milne-Edwards, 1881, and his own 
new genus, T’ropiocdris, 1888, in a separate family Tropio- 
caridz. But as he says that T’ropiocaris in many of its parts 
approximates so nearly to Acanthephyra and Notostomus 
that it can only be considered as a separate genus for the 
