120 Mr. J. S. Bowerbank on Carcharodon Megalodon. 



§. Fusillus, Lowe. 



45. AcHATiNA ORYZA.— Jf. tviticea ^. edentula, Prim. 61. t. 6, 

 f. 26. Differt ab H. triticea, Lowe, apertura spira longiore, spira 

 breviore, plica ventrali nulla obsoletissimave, columellari plane 

 nulla. 



Hab, in Portu B^, 



46. AcHATiNA TUBERCULATA. — Achat. oryzcB proxima. Pif- 

 fert testa majore, forma ventricosiore (ut in Achat, tornatellina 

 Lowe) magis abbreviata, apertura longiore, spira breviore, ven- 

 tre sursum obsolete calloso-tuberculato. 



Hab, in Portu S*°. 



47. AcHATiNA TEREBELLA. — Differt ab Achat, oryza testa 

 graciliore teiiuiore inter illam et Achat, gracilem, Lowe, inter- 

 media^ huic propior, sed colore magis fusco-corneo intensiore, 

 minus splendide hyalino-lsevi, testa ventricosiore, spira breviore, 

 apertura longiore, labro subarcuato-prominente distincta. 



Hub. in Portu S*°. Coll. Wollaston et Armitage. 



§. Acicula, Risso. 



48. AcHATiNA PRODUCTA. — Achat, acicula, MiilL, affinis, sed 

 testa duplo majore solidiore robustiore aspectu omnino distincta. 

 Ab Achat, gracilis Lowe, testa solidiore nee hyalina, apertura 

 sursum oblique retro producta et angustata, columella basi pro- 

 minente distincte truncata v. emarginata differt. 



Hab. in Deserta Australi. 



§. Amphorella, Lowe. 



49. AchAtina mitrtformts. — Achat, tornatellina, Lowe, affi- 

 nis. Differt testa graciliore magis elongata, apertura breviore, 

 spira longiore, &c. Species proculdubio distincta. 



Hab. in Madera. 



X. — On the probable Dimensions of Carcharodon Megalodon 

 from the Crag. By J. S. Bowerbank, F.R.S., L.S. &c.* 



When we view small portions only of extinct animals, such as 

 teeth or fragments of bone, there is often a considerable degree 

 of difficulty in picturing in our minds anything like the size and 

 proportions of the creature to which such remains have belonged, 

 and it is with a view of endeavouring to realize in our imagina- 

 tions the fish to which the great teeth of Carcharodon Megalodon 

 from the Crag has belonged, which has induced me to introduce 

 this subject to your notice on the present occasion. 



* Communicated by the author, having been read at the Meeting of the 

 British Association in Julv, 1861. 



