PLATE CV. 



OSTREA ISOGNOMUM : testa equivalvi : lobo laterali majore. 



Linn. Lud. Ulr. 533. n, 120. — Gmel SijsU Nat. 

 3338. n^.-^Eeha Mus. 3 jf. 91 . / 7. 



Pern A Isognomum : testa compressa, superne in aJam curvatam 

 vel obliquam elongata ; basi transversa, prelonga, 

 in rostrum anterius producta. Lamarck Anivu 

 sans Verteh. t. 6. p. 1 . p. 140. 



Notwithstanding tliat the figures of several varieties of this 

 curious shell are to be found in the works of Seba, Rumphius, Klein 

 and other early writers, it has ever been considered as a scarce shell. 

 Gmelin observes, in speaking of its being an inhabitant of the Indian 

 Ocean, habitat rarior et pretiosa in Oceano Indico." Our spe- 

 cimen is from the South Seas, one of the finest and most choice 

 examples among those which were brought to England by the 

 celebrated Captain Cook, and which was presented by that eminent 

 navigator to Sir Ashton Lever : it is probably the most perfect and 

 illustrative specimen of the species known, for in all the figures 

 which we have seen, the larger extremity appears broken and more 

 pointed, while in the present shell it is dilated, and forms a rounded 

 instead of pointed termination. This shell is known among English 

 collectors by the name of the Great Black Hound's-ear, and some- 

 times the Australasian Black Hound*s-ear ; the French distinguish 

 it by the name of Perne bigorne. 



