Description of the Argulus Catostomt. 307 
In endeavoring to demonstrate, in the Argulus, the eleven pairs of 
parts or organs which are commonly found posterior to the antenne, 
in all the Crustacea, we proceed thus :—as reckoned above, there 
are, including the tail, six pairs of branchial members; next, two 
pairs of prehensile, emidelalie the suction legs as such; then, two 
pairs of maxille ; and lastly, a pair of mandibles RE into 
the siphon. The bony arch, situated on the medial line, is not un- 
like the bony wall which in other Crustacea forms the anterior bor- 
der of the buccal aperture. 
J. V. THompson, the author of many curious discoveries con- 
cerning the metamorphosis of the Crustacea, has published* a short 
notice of an anomalous parasite which he names Sacculina Carcint, 
found by him on the Carcinus Menas. This parasite he considers 
identical with the Argulus armiger of Mixer, figured by Stas- 
BER in plate 6 of his Natuurkundige Verlustigingen, (Haarlem, 
1769-78)—a species we cannot find recognized in any work since 
the time of Miitter, except in the Encyclopedie Methodique, (In- 
sectes, Art. Argule.) Mr. T. has not seen it in the mature state, 
and it is therefore at present impossible to ascertain its relations to 
the A. foliaceus or A. Catostomi. The larve appears to be totally 
destitute of all organs of manducation. We hope to hear further 
respecting so remarkable an animal. 
The buccal apparatus of the Pandarus alatust has, as from its sim- 
ilarity of habits might be expected, some resemblance to that of the 
Argulus, but the siphon when at rest, lies in a reverse direction. 
An extended comparison between the trophi of these two genera, 
would be of great interest. 
We are well aware that the foregoing account of the Argulus Ca- 
tostomi is not complete. . Many particulars of its habits and meta- 
morphoses, together with many important details of anatomy are yet 
to be discovered. Some of these deficiencies we hope to wie 2 at 
a future day. 
“New Haven, Conn., October, 1836. 
EXPLANATION OF THE PLATE. 
Fig. 1. Under view of the Argulws Catostomi, Seminal pouches r, F- 
Fig. 2. Posterior branch of the first pair of antenne 
Fig. 3. Termination of the second pair of antennwe. 
* Entomological Magazine, (8vo. London,) Vol. 3, p. 452—456. April, 1836. 
+ Described and figured by H. Miine Epwarps, in Annales des Sciences Natu- 
relles, (8vo. Paris,) tome 28, p. 78—86, and plate 8 
