FAMILY SPHAROMIDA. 131 
The result is that of seven species referred to the genus 
Cassidina (M.-EHdw.) at least one, and probably two, must 
be cancelled as synonyms, while the five others, having only 
a broad body and areduced exopod of the uropods in common, 
must be referred to at least four genera, and two of these, 
established respectively in 1887 and 1901, have been so 
imperfectly described that reference to genus or to group of 
genera is impossible. This state of things illustrates ex- 
cellently the confusion arising from extreme want of guiding 
principles of investigation, etc., in the study of the family. 
(7) Chitinopsis (Whitelegge).—The type is C. spatu- 
lifrons (Whitel.), of which [ have not seen any specimen. 
No other species has been established, but I have inspected a 
new form allied to the type. The two species have a curious 
aspect, but the genus is in reality so closely allied to 
Cassidina that it can only be considered a sub-genus, and 
ought perhaps to be cancelled. It seems to be impossible to 
find any character of some importance; the characters used 
in the conspectus are, I hope, tolerably practical. 
(8) Cassidinidea (n. gen.).—This genus is established on 
Nesa ovalis (Say). In the British Museum I saw three 
specimens presented by Thomas Say; the Copenhagen 
Museum possesses a few specimens from Grenada, and one 
specimen from Cincinnati. Cassidina lunifrons (Richard- 
son) belongs probably to the same genus; according to a 
figure published by Miss Richardson, it is very closely allied 
to N. ovalis, if it may be assumed that a portion of the 
basal joint of both antennule in reality is the front end of 
the broad epistome. It may be useful to add a few notes on 
C. ovalis, as nothing has been published on this species 
since the description of Say in 1878. An adult female 
measures 6 mm. in length and 3°3 mm. in breadth; judging 
from Miss Richardson’s figure, C. lunifrons is proportion- 
ately a little broader, and its head somewhat broader than in 
our species. The body is very depressed, its upper surface 
grey-mottled with brown and dark brown. The epistome is 
a little more than twice as broad as long at the mesial line, 
vou. 49, part 1.—NEW_SERIES, 10 
