Mr. J. G. JeflPreys on the genus Scissurella. 321 



by me. In the first-mentioned species, too, the spire is laterally 

 compressed, as in Stomatia, and is not so trochiform as in the 

 others ; and if the family of Scissurellada (as proposed by Dr. 

 Gray in his " List of the Genera of Recent MoUusca '') is adopted, 

 I venture to suggest that for the species in question and others 

 which possess a similar organization and form, the generic name of 

 Schismope (ab a')(^L(7^7]j scissura, et owr}, foramen) would be appro- 

 priate*. Trochotoma, Pleurotomaria (if indeed Scissurella differs 

 from it), and other fossil genera, may then form part of the same 

 family ; as no system of classification can be complete in which 

 what are usually termed '^ extinct " forms are not comprised. 

 Sowerby, in his " Genera of Recent and Fossil Shells," took the 

 characters of Scissurella from a species of the Calcaire grossier of 

 Grignon, and not from any of the species described by D^Orbigny, 

 who is not likely to have overlooked the remarkable structure of 

 the scissural foramxcn. The position given to Scissurella by the 

 late Professor Forbes in the 'British Mollusca' (viz. between 

 Adeorbis and lanthina), cannot, I think, be right; because the 

 last-mentioned genera belong to very different families. These 

 minor problems in natural history are very interesting ; and I 

 hope my friend Mr. Clark will be able next summer to obtain 

 and describe the animal inhabitant of Adeorbis subcarinata, and 

 thus increase his valuable stock of observations on the British 

 MoUusca. 

 58 Montagu Square, St. David's Day, 1856. 



P.S. Having submitted the above to Dr. Gray, I have been 

 favoured with his remarks on the subject ; which, with his per- 

 mission, I will subjoin to my communication : — 



" British Museum, 6th March 1856. 

 " My dear Sir, 



" I have read your note with much interest ; and I have little 

 doubt the genus Scissurella belongs to the great group which 

 has been called Scutibranchia, Rhiphidoglossa, or Trochoida, 

 characterized by the structure of the gills, the lateral membrane 

 and tentacles, the peculiar disposition of the teeth and organs of 

 digestion, and by its generally forming a pearly shell. 



"This group consists of the genera Trochus, Rotella, Turbo, 

 Haliotis, Stomatia, Stomatella, Fissurella and Parmophorus of 

 Lamarck : and perhaps, according to the theories of some con- 

 chologists, especially such as study the productions of a small 

 region only containing a very few representatives of each family, 



* The only recent species with which I am acquainted (Sc. striaiula. Ph.) 

 is Uttoral. All the species of Scissurella proper apparently inhabit deep 

 water. 



Ann. <Sf Mag. N. Hist. Ser. 2. Vol. xvii. 21 



