J1ALACOZOA. GASTEROPODA. NUDIBRANCHIATA. 191 



2. Bulllna truncdta. Semipllcate Bullina. 



Shell subcylindrical, thin, transparent, glossy, with distinct 

 shallow snlci extending over half its length from the left ex- 

 tremity, which is truncate, with a wide and shallow umbilicus, 

 exposing a whorl and the central obtuse apex ; the aperture 

 extending the whole length, very narrow for about half, then 

 ovato-oblong, the outer lip thin, the columella visible for a 

 third of iis length, ..and there reflected ; the colour white. 

 Length nearly two-twelfths, breadth half the length. 



Found by me in shell sand from the beach near Aberdeen ; 

 also in shell sand, from Cruden Bay, sent by Mr. Alex, Mur- 

 - ray. 



Btilla truncata, Adams, Linn. Trans, i. PI. 1. f. 12. Bulla 

 truncata, Flem. Brit. Anim. 293. Bulla truncata. Mont Test, 

 Brit 223. PL 7. f. 5, 



3. Bullma cylindracea, Cyllndriv Bullina. 



Shell subcylindrical, rather thin, or thick, transparent, glossy 

 rugose, with strong growth-lines, and covered with a greenish 

 or yellowish epidermis, truncate, with a deep umbilicus, expos- 

 ing two whorls ; the aperture extending the whole length, ex- 

 tremely narrow for nearly two-thirds, then ovato-oblong, the 

 outer lip thin, the inner reflected, and having a slight promi- 

 nence at the end of the columella ; the colour of the shell 

 hyaline-white. Length four-twelfths, breadth less than half 

 the length. 



Frequently brought up by the lines adhering to ascidise, 

 and not uncommon in shell shand, on the beach at Aberdeen, 

 where it has become opaque and white. Found also at Slains 

 by Mr. Alex. Murray, and at the Cove, by Mr. Fergusson. 



Bulla cylindracea. Penn. Brit. Zool. iv. 1 17. PI. 70. f. 85, 

 Bulla cylindracea. Mont. Test Brit. PI. 7. f. 2. Bulla cylindra- 

 cea. Flem. Brit Anim. 293. 



ORDER VIII. GASTEROPODA NUDIBRANCHIATA. 



Respiratory apparatus consisting of branchial tufts or 

 papillae on the back, exposed, and symmetrically arranged, 

 whether in the middle or along the sides. 



