Bulla. MOLLUSCA. BRANCHIFERA. 295 



EXTINCT SPECIES. 



1. B. convolula — Cylindrical, smooth ; aperture linear, expanded a little 

 way from the base ; vertex obtuse, perforated — Sower. Min. Conch, t. 

 cccclxiv. f. 1. — In Crag. 



2. B. constricta — Subcylindrical, contracted in the middle ; vertex trun- 

 cated, perforated ; base obscurely striated ; aperture linear, expanded at the 

 base Sower. Min. Conch, t. cccclxiv. £ 2. — London clay. Barton. 



3. B. elliptica Elliptical, elongated, transversely striated ; vertex perfo- 

 rated ; aperture widest at the base — Sower. Min. Conch, t. cccclxiv. f". 6 



London clay, Barton. 



4. B. attenuata. — Elliptical, transversely striated ; superior portion elon- 

 gated, truncated, perforated ; aperture curved, widest towards the base ; strife 

 distant in the middle. — Sower. Min. Conch, t. cccclxiv. f. 3.— London clay. 

 Hordwell. 



5. T&.Jilosa. — A fragment. " Its numerous striae and expanded lip distin- 

 guish it from B. attenuata."— Sower. Min. Conch, t. cccclxiv, f. 4. 



