108 Mr. "W. Clark on the Animals of the Ballidse. 



groove between the head and foot-discs. The branchial plume 

 is deposited in a cavity across the neck. The buccal mass is a 

 light fleshy palate, and may be seen through the head-lobe; 

 the mouth leads by a long linear oesophagus to the stomach, 

 situated in the last convolute cavity of the shell, in which is fixed 

 a gizzard of three very small, dark brown, similar-formed, mi- 

 nutely dotted, oval, coriaceous plates, which can be seen in action 

 through the transparency of the basal volution. 



It appears that the only difference between this animal and 

 that of B. cylindracea is, that in this the disc-flaps are more de- 

 veloped, and the eyes are distinctly visible ; I therefore consider 

 all the general remarks on the last species, not mentioned to 

 prevent repetition, as applicable to B. truncata, which I think is 

 appropriately deposited in the genus Bulla. The Bullida, like 

 the Helicidce, are hermaphrodites with mutual congression, and 

 are oviparous. 



Bullaa, Lamarck et auctorum. 

 Philine, Ascanius et Loven. 



The type of this section of the Bullida is the Bullaa aperta of 

 authors. This ancient species is so familiar with every malaco- 

 logist, that to describe the external organs would be useless ; the 

 internal structure essentially agrees with that of B. kydatis, and 

 is described and illustrated by M. Cuvier. 



As to the minor Bullace of the Exmouth coast, the rare B.prui- 

 nosa is our own discovery, and with the B. catena of Montagu 

 and B. punctata of Adams were described by us many years ago 

 in the ' Zoological Journal,' vol. iii. p. 339. To reproduce them 

 would be an improper occupation of the valuable pages of the 

 * Annals ' with old matter, and having no additional notes we 

 only refer to our former descriptions, but we shall be glad to 

 review them. 



In conclusion, I observe, that a re-examination and comparison 

 of all the minute species of both tribes of this family with each 

 other, and with those that have not as yet been seen, may require 

 new genera ; but as the case now stands, I think that Bulla and 

 Bullaa are sufficient. We all must object to the splitting and 

 torturing mere specific differences to fabricate useless genera. 



I am. Gentlemen, your most obedient servant, 



William Clark. 



