HEPTABRANCHUS. 59 



olavate, the clubs lamellar; the mantle-margin is finely 

 crenated, and the lobe-like gills are surrounded by an ele- 

 vated circular disk with an undulated margin. A single 

 species only, from Rochelle, is at present known. 



Genus HEXABKANCHUS, Ehrenberg. 



Tentacles dorsal, clavate ; labial feelers dilated, broad, and 

 crenate. Gills tree-like, in a circle round the anal aperture, 

 each retractile into its proper cavity. 



Ex. H. Adamsii, Gray, pi. 03, fig. 9. 



In the figure we have given to represent this genus the 

 proboscis and labial feelers ore protruded, and the former is 

 distended, a circumstance that frequently happens to these 

 animals in a sickly state, and some time previous to their 

 death when kept in captivity. The number of the branchial 

 plumes is usually six, whence Ehrenberg's generic name. 



Species of Hexabranchus. 



Adamsii, Gray. pretextus, Ehrcnb. 



cardinalis, Gould. Sandwichensis, Quoy and 

 laciniatus, Cuv. Gaun. 



marginalis, Quoy and Gaim. sanguineus, Eiijip. 



Genus HEPTABRANCHUS, A. Adams. 



Tentacles dorsal, clavate. Gills tree-like, in a broad, 

 lunate series, each gill retractile into its proper cavity. 



Ex. H. Bumettii, A. Adams, pi. 63, fig. 10. 



The splendid species upon which this genus is founded 

 is of large size, about six inches long, and of the most 

 brilliant colours : the vent is tubular, and the mantle 

 does not entirely cover the foot behind ; the tentacles are 



