UNIVALVES. 



PLATE LIIL 



Genus. OVULA. 

 Character. Shell, spire short and involved ; body oval ; the opening of the mouth 

 narrow, and Teaching the whole length of the shell, having no teeth like those of 

 the Cypraea, on the body and mouth ; an open channel or beak standing at each 

 end of the shell. 



Species. 

 No. 1. Ovula alba. Shell of a white colour, egg-shaped ; mouth of a dark brown, 



oblong, and longitudinal, pointed at each end, undulated on the body and 



cheek, and of an irregular form. A native of New Zealand. 

 No. 2. Ovula pharetra. Shell pale red, streaked with red ; mouth yellow, 



swelling out at the bottom, and taper at each end ; body strongly tubercu- 



lated. This shell is found only in the Asiatic Seas. 

 No. 3. Ovula aspera. Shell oblong at each end, elegantly striped across with 



red veins ; the mouth yellow. Native place unknown. From a shell in 



the British Museum. 



Genus. PROSCENULA. 



Character. Shell flattened, hollow, having a proscenium, or small platform, 

 placed on the under side, in the manner of a stage ; the outer side of the shell 

 rounded, or pointed like a shield. 

 No. 1. and 2. Proscenula virldis. Shell green and white on the under side, of 



an oval form, and something resembling a Patella. Native place unknown. 

 No. 3. Proscenula grisea. Shell gray, yellow within, except the stage, which is 



white. Native place unknown. 

 No. 4. Proscenula nucleata. Shell pale brown ; the mouth orange colour, the 



stage white. A native of the South Seas. From a specimen in the British 



Museum. 



Genus. SERPULA. 

 Character. Shell spiral, involved, twisted like a worm, sometimes straight, hol- 

 low at each end, unequal in breadth, and irregular. 



No. 1. Serpula variegata. Shell smooth, circular, involved, irregular in form, 

 of a pale gray and brown colour. Found in the islands in the West Indies. 



REMARKS. 



The genus Ovula has been described by Bruguiere, and the characters of the Serpula have 

 been ably laid down by Pennant, as well as by Linnaeus himself, and are easily distinguish- 

 able at the first sight. 



The genus Proscenula is now described for the first time, and differs from the Patella in 

 the construction of its inner stage or membrane ; its species are very numerous, which makes 

 it rather extraordinary, that no one should have described it before. It also bears consi- 

 derable analogy to the genus Haliotis in its general form. 



