im.] CENUS 5IACLURITE. 311 



an Ammonite, or I^aiitiliis ; and was noticed as such 

 by Mr. Maclure in his geok)gical observations, page 

 ^7» We first observed an impression of it in the com* 

 pact limestone which forms a portion of the bank of 

 Lake Erie, near Eighteenmile creek, mixed with Ca- 

 ryophilloca, and subsequently at Basin Harbour, on 

 Lake Cbamplain, where several more perfect indivi- 

 duals occurred ; several good specimens were lately 

 sent by a gentleman of Kentucky, to the Philoso- 

 pliical Society, one of them, an impression, 10 or 12 

 inches in diameter, and another exhibiting a perfect 

 vertical section. 



Mr. Samuel Hazard, a member of the Academy, 

 presented to our cabinet a collection of fossils collect- 

 ed by himself, in Kentucky, amongst which were 

 some specimens of this shell. Sometime afterwards 

 Mr. Clifford, of Kentucky, presented me with fine 

 specimens which he brought from Tennessee river. 



A careful examination of all these individuals, in 

 their several states of preservation, presented to me. 

 the common characters of a discoidal form, flat spire, 

 very large umbilicus, and entire cavity ; the last trait 

 distinguishes them from Nautilus. Tlie genera to 

 which it makes the nearest approach are Solarium 

 and Delphinus of Lamarck, but it is separable from 

 them by the characters by which I indicate this new 

 genus. 



