6lO TBANS. ST. I.OUIS ACAD. SCIENCE. 



centres are closer than the distances between the crests of the rings. 

 The surface of the shell is slightly striated parallel with the wave- 

 like markings just mentioned. The calcareous matter is partly 

 preserved, but only a portion of shell about five centimetres long 

 was obtained. Its diameter is about one centimetre. 



Formation and Locality. — This species occurs in the " chert 

 bed" of the Niagara formation at Hamilton, Ont. 



Cyrtoceras reversum, nov. sp. 

 Plate 7. Fig. 8. 



Only the internal cast of this species is known. Its form is 

 rapidly tapering, with a considerable curvature, until it ends in 

 a rounded point. The surface is smooth, barely indicating the 

 position of the septae, which are about equal in length to the diam- 

 eter of the f-hell at that place. The convex side of the septae is 

 directed towards the body-chamber. The siphuncle is unknown. 

 Only the smaller end of this species is known ; with the largest 

 chamber, having a diameter of i .25 centimetres, from which to the 

 pointed extremity there is a distance of about four centimetres. 



Formation and Locality. — It occurs in the lower beds of the 

 Niagara limestones at Limehouse Station on G. T. R. 



LiTUlTES NIAGARENSIS. 



Plate 7. Fig, 9. 



Tube large, and consisting of about two whorls when com- 

 plete ; section circular(.'') ; siphuncle unknown; septae concave, 

 and numerous. The inner extremity of shell is unknown. The 

 first whorl has a diameter of about 3.5 centimeters. After the 

 completion of about one and a half whorls, the exterior whorl be- 

 gins to separate, until, at the completion of the second turn, it is 

 three centimetres distant, near which it terminates. The whole 

 spire is about twelve centimetres across, and the diameter of the 

 largest end of tube is not less than four centimetres (but it is much 

 obscured). The diameter of the shell in the first whorl is rather 

 more than one centimetre. There are about five very concave septte 

 in the length of two centimetres in the middle portion of the shell. 

 The exterior surface appears to have been nearly smooth. 



Formation and Locality. — Only one specimen has been ob- 

 tained, and that was presented to the writer by Col. Grant. It 

 occurs in the Niagara limestone at Hamilton, Ont. 



