CYAMUS THOMPSONI. 97 
of C. ceti, which we have represented in our figures in 
page 90; and in all, the penultimate joint is large and 
angulated in the middle of its lower edge. 
The specimen was obtained by Mr. William Thomp- 
son, of Weymouth, attached to an individual of Hy- 
peroodon bidens captured in Portland Roads in 1854. 
This is the species referred to by Mr. Spence Bate in 
the ‘Annals of Natural History,” for February, 1857, 
2nd Series, under the name “ C. 

?C. gracilis. 
Gosse,” as stated by Mr. Bate himself in the same work, 
2nd Series, vol. xx. p. 525, where it is referred to 
C. Thomson [Thompsoni|. Gosse, Ann. Nat. Hist.,” 
vol. xviil. [xvi.] 1855. 
In our introductory observations on the genus, we 
have seen that M. Roussel de Vauzeme had not observed 
any species of this genus on any of the dolphins; but 
the capture of this specimen by Mr. Gosse disproves 
such a statement, whilst M. Guérin Meéneville, in his 
**Tconographie du Réegne Animal,”* has described and 
figured a species under the name of C. delphinii, taken 
upon the generative organs of the dolphin on the coast 
of the Antilles. It is of an oval-elongated form, with 
the segments of the body touching each other at the 
sides except the terminal ones, which are a little gaping. 
The great joint of the second legs bears a strong tooth on 
its under edge, the branchial filaments (one on each side 
of the third and fourth segments) are very short, and 
much shorter than the legs. The basal articulations of 
the hind legs are strongly dentated and various in form. 
Mr. Spence Bate (Cat. Amph. p. 366) considers this 
species to be only a variety of C. gracilis. It has, how- 
ever, to be determined whether the animal is uniform 
in its residence on the dolphin, or only exceptional, as 
* Crust. texte, p. 25. 
VOL. II. H 
