FOSSILS. 603 



angular band on the volution is the only means of determining its 

 generic relations. 



This differs from any of the described species of Murchisonia from 

 American localities. Arisaig, coll. J. \Y. I '. 



Murchisonia acicidata, Hall. Shell slender, very gradually tapering, 

 volutions about six or seven, the last ones moderately vcntric> 

 aperture elongate-oval or ovate, rounded at the anterior margin, 

 columella plain ; volutions marked by a distinct band along tin- 

 centre, and a sub-sutural carina marking the upper side of the volu- 

 tions ; surface striated. Arisaig, coll. J. ~\\. D. 



Pleurotomaria. A flat species with four turns. Arisaig, Dr Honey- 

 man. Nictaux, J. W. D. 



Holopea revc?'sa, Hall (Fig. 211). Shell small, sinistral; spire 

 depressed, volutions about three ; the two first small and gradually 

 expanding, the last one rapidly expanding and ventri- „. 211 

 cose ; aperture wide expanded ; suture impressed. Sur- 

 face unknown. This shell has the general form of Holo- (ft J 

 pea, but I have seen only a single specimen, which is a 

 cast. It is remarkable and readily recognised from the sinistral spire. 

 Arisaig, coll. J. W. D. 



Bucania trilobita, Hall. Arisaig, East River, Nictaux, coll. J. W. D. 



Bellerophon expansus (?), Sow. Arisaig, Dr Honey man. 



Bellerophon carinatus, Sow. Arisaig, Dr Honeyman. 



Platyschisma helicites, Sow. Arisaig, Dr Honeyman. 



Acroculia helicites, Sow. Arisaig, Dr Honeyman. This and the 

 three last species are from the lists of Dr Honeyman and Mr Salter. 



Orthoccras punctostriatum, Hall (Fig. 212). Shell slender, very 

 gradually tapering, almost cylindrical. Septa distant about one-third 

 the diameter. Siphuncle central ; section circular. Surface very 

 finely striated with unequal undulating striae, the interstices between 

 which are punctas, which are oblong indentations often becoming 

 confluent. 



* 



Fig. 212. Orihoceras punctostriatum. Fig. 213. 0. elegantulum, and portion magnified. 



fek,',ii\i» 



This species is remarkable for its extremely gently tapering form : 

 the fragment of more than an inch long, showing scarcely a per- 

 ceptible diminution in diameter. There are twelve and a half chain- 



