28 Mr. C. Spence Bate on a new Species of Spheroma. 
Caradina tenuis. FP. II. fig. 1. 
The distinction between this and the preceding species 
consists in the more slender proportions generally of the latter, 
and in the position of the teeth on the rostrum, which in 
C. varians has the basal tooth on the dorsal surface further 
from its base, and the infero-subapical tooth a little poste- 
rior to the supero-subapical tooth, whereas the tooth that is 
situated near the base of the inferior surface of the rostrum 
is in C. tenuis placed but little posterior to the SUBIR BL 
tooth. 
In all other respects the two species agree; so that we think it 
not at all improbable that they may be but the two sexes of one 
species. To this supposition strength is given from the circum- 
stance that, while we took numerous specimens of C. varians, 
most of which were carrying ova, none of the few specimens 
of C. tenuis were so. But to this negative evidence we have to 
oppose another of a negative character also, which 1s that we 
have no experience of any species of Prawns that bear such 
sexual distinction, both as to size and form. The length of C. 
varians is an inch, that of C. tenuis half an inch. 
Isorpopa. 
Some time since, Dr. Fritz Miller sent us some specimens 
of an Isopod which he has named Spheroma terebrans, pro- 
cured from timber that had been immersed in the sea; since 
which we have received, through Mr. Brisbane Neill, some very 
similar specimens from Capt. Mitchell, of the Madras Museum. 
A close examination is required to distinguish a specific charac- 
ter separating these from the Brazilian specimens; and I think 
that the only one that can be relied upon is, that the pointed 
and hook-shaped termination of the appendage of the mandible 
in Miiller’s specimens, is represented in those from Madras 
by a flat broad joint. I therefore think that, minor variations 
being taken into consideration, together with the distance of 
the two habitats, we do not err in considering the following a 
distinct species from that found by Fritz Miiller. We therefore 
propose for it the name of 
Spheroma vastator. Pl. I. fig. 4 
The animal is of a long oval shape, without any distinct coxee, 
and furnished with four longitudinal parallel rows of tubercles 
or blunt teeth on the three posterior somites of the pereion and 
the anterior portion of the pleon. 
The eyes are round and prominent. The superior antenne 
have the first joint of the peduncle broader than the second, 
