178 C. Spence Bate on the Penwidea. 
p- 121) that I think they are the same; unfortunately Heller 
describes the inferior margin of the rostrum as being “ eden- 
tulous,” whereas his figure 2, plate x1., shows there are three 
teeth on the lower margin. 
Peneus carinatus, Dana, also, it appears to me, belongs 
to this species, the only distinction being that Dana and 
Heller’s species have three teeth on the lower margin, and 
the type of P. indicus has four or five; but these are not 
distinctly portrayed, and are more elevations than distinct 
teeth. 
Undoubtedly the number of teeth on the rostrum is a very 
constant feature in normal and well developed forms, and 
may be relied upon as representing some important structural 
character in the animal. Occasionally, however, some forms 
exhibit an effort to abnormally increase or diminish the number; 
but whenever this is the case the teeth exhibit generally an 
imperfect and enfeebled condition. This appears to be the 
case with the type specimen; and I am induced to think that 
they are merely varieties of the following species. 
There are other specimens in the collection labelled “ P. 
indicus,’ some of them from the coast of Coromandel; but 
these bear the impress of having been named by others than 
the veteran author of the ‘ Histoire des Crustacés ;’ they agree 
more nearly with Peneus setiferus of the West Indies, and 
require a closer examination than | devoted to determine them 
specifically. 
Peneus monodon, Fabricius. 
This species is extremely like P. indicus ; but, according to 
Milne-Edwards’s definition, the rostrum only presents three 
teeth on the lower margin, and the flagella of the first pair 
of antenne are shorter. 
Length of types of Milne-Edwards 38 inches; of Fabricius 
7 inches. 
Hab. Indian seas. 
The type specimens are all small and immature animals; 
but there are larger specimens in the collection that agree with 
Fabricius’s description as referred to by Edwards. A close 
analysis of this species compared with P. irdicus makes me 
very dubious of any truly specific character, beyond the 
“much shorter length of the flagella of the first pair of an- 
tenn,” and there being only three teeth on the lower margin 
of the rostrum. 
I am induced, from the great resemblance in the form of the 
ventral plates in the females, to accept the conclusion that 
P. indicus, Edw., P. monodon, Fabricius, P. semisulcatus, 
