494 NUDIBRANCHIATE MOLLUSKS. 



Among new and interesting forms of those Molluscous 

 animals which are denied any calcareous defence in the 

 form of a shell, and the breathing organs of which are 

 consequently exposed, hence procuring them their name, 

 Nudibranchiata, may be mentioned two new species of 

 Dendronotus, one of which (D. stettifer, Adams and Reeve,) 

 is of a pale flesh colour, marked with undulating vertical 

 vermilion lines, freely anastomosing towards the foot, and 

 the veil overhanging the head provided with a star- 

 shaped tentacular appendage on either side. The other 

 species of this curiously-shaped genus (D. tenettus, Adams 

 and Reeve,) adheres like the former to floating Fuci; 

 crawls pretty briskly, and swims, when detached, by lateral 

 inflexions of the body. Among the Ttoridida, the Poly- 

 cera cornigera, (Adams and Reeve,) is one of the most 

 beautiful of the family, the body being of a pale straw 

 colour, beautifully marked with bright vermilion, which 

 covers entirely the dorsal portion, and descends in nu- 

 merous Vandykes towards the foot ; there is a row of 

 bright ultramarine spots on the anterior tubercle, and 

 another row of the same colour extending across the top 

 of the head. A species of the genus Hexabranchus of 

 Ehrenberg, which I have named H. sanguinolentm, is also 

 of the most lovely colours, but yet is made to yield the 

 palm to the type of a new genus, which may be termed 

 Heptabranchus, and which I have dedicated, by permission, 

 to Sir William Burnett, the Medical Director-General of 

 Hospitals and Fleets. The nearest approach to this pecu- 

 liar form of Doridida3 (Heptabranchus Burneltii,} appears 

 to be the animal named Doris Sandwichienne of the 

 "Voyage de la Bonite;"* but in that Mollusk the mantle 



* Torn. 25, f. 1, 2. 



