Bare British Mytilus. - 353 



This very elegant species in shape very much resembles 

 a small B. lignaria; but is of a more conic oval shape, with 

 the volutions more loosely connected ; the crown is umbili- 

 cated, and, together with the pillar, pure white. On the body 

 are regular, rather broad, alternate, transverse bands of white 

 and pale rufous brown ; and round each of the white belts is 

 a regular line of very minute raised granular dots. 



Found near the Land's End. (Mus. Clark,) 



Bu'lla hya^lina [^Turtoii], Roxania Leach, 



Testa ovata, hyalina, lasvi; aperture basi dilatataj columella umbilicata ; 

 corona planata, canaliculata, umbonata. 



Shell oval, transparent, smooth ;, apertura dilated at the base ; pillar 

 umbilicate ; crown flattened, channelled, umbonate. 



It something resembles the Bulla umbilicata; but is shorter, and of a 

 more oval shape, with the aperture more dilated, and is of a crystalline 

 transparency. At the base of the inner margin there is a reflection of the 

 pillar, forming a slight groove or umbilicus ; and the central umbo on the 

 crown is very distinct and prominent. The last two marks seem to fix it 

 in the genus Cymba of Lamarck and Sowerby; but we have not remarked 

 the sharp plaits on the pillar. 



Found abundantly on the coast about Newcastle; whence it 

 was sent us by Mr. Alder. We also discovered it near the 

 Land's End, in Cornwall. {Mus. Alder, Clark,) 



BuLL^^A puncta'ta [7wr/o?z], Bulla punctata Adams, Linn, 

 Trans, vi. t. i. fig. 6, 7j 8. 



Testa ovata, hyalina, lineis transversis impresso-punctatis ; corona 

 canaliculata. 



Shell oval, transparent, with transverse lines of distinct impressed dots. 



The accurate observations of Mr. Clark, who favoured us 

 with specimens, have fully distinguished this species from 

 B. catena of Montagu. The shell is something smaller, of a 

 more oval shape, with the crown more flattened ; and, instead 

 of oval, raised, chainlike points, which form the lines in B. 

 catena, the lines in this species consist of distinct impressed dots. 



Mr. Clark has also been able to ascertain, that, in B. ca- 

 tena, the animal is of a yellowish white, and furnished with 

 a gizzard ; but that the animal of B. punctata is of a blackish 

 grey colour, and destitute of any trace of gizzard. 



Found by Mr. Clark, near Exmouth. 

 Bideford, Devon, May 1. 1834. 



Art. IX. A Notice of Localities, Habits, Characteristics, and 

 Synonymes of a rare British Sj^ecies ofMytilus. By Mr. Wil- 

 liam Williamson, Jun. 



My'tilus subsaxa' tilis [^Williamson']. — A species of 

 Mytilus has been occasionally found on various parts of the 

 Vol. VII. — No. 40. a a 



