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. 



Grosse," as stated by Mr. Bate himself in the same work, 

 2nd Series, vol. xx. p. 525, where it is referred to 

 C. Thomsoni [Thompsoni']. Gosse, "Ann. Nat. Hist.," 

 vol. xviii. [xvi.] 1855. 



In our introductory observations on the genus, we 

 have seen that M. Roussel de Vavizcme had not observed 

 any species of this genus on any of the dolphins ; but 

 the cajDture of this specimen by Mr. Gosse disproves 

 such a statement, whilst M. Guerin Meneville, in his 

 " Iconographie du Regne 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 



