in Deers and Antelopes. 79 



matter floats, and the rest of the fluid becomes turbid and 

 milky. Cold alcohol digested on another portion took up a 

 good deal of yellow viscid matter ; and when evaporated fur- 

 nished also some extractive, soluble in water, probably the same 

 as that aflbrded by the aqueous solutions. Boiling alcohol, di- 

 gested on the residuum, takes up more of the yellow matter, 

 which, on evaporation, affords a more resinous looking residuum, 

 the surface of which is covered with a greasy film, also sapo- 

 nifiable by caustic potash. Alcohol, digested on what remained 

 after the action of aether, dissolved only a trace of saline matter ; 

 and the residuum, after exhaustion by aether, had the appear- 

 ance of thin flakes of pearly cuticle, coloured yellowish-brown, 

 insoluble in strong acetic acid, but soluble in potash, from which 

 it was precipitated by acetic acid. A portion of these flakes, 

 when strongly heated, left a white ash, consisting of carbonate 

 and phosphate of lime, carbonate of soda, and chloride of so- 

 dium. The material then appears to consist of a number of hairs, 

 with a quantity of delicate, cuticular flakes, the whole intimate- 

 ly mixed with a dark matter, composed as follows : a brownish, 

 viscid, oily substance, probably containing resin ; a volatile odoi 

 rous principle ; extractive, soluble in water and alcohol ; colour- 

 ing matter, which adheres to the flakes of cuticle ; lactates of 

 soda and lime, a trace of phosphate of lime, and chloride of so^ 

 dium in considerable quantity."" 



Remarks on the Difficulty of distinguishing certain Genera of 

 Testaceous Mollusca by their Shells alone, and on the Ana* 

 malies in regard to Habitation observed in certain Species. 

 • By John Edward Gray, Esq. F.R.S. &c.* 



It has been a very common error, both among conchologists 

 and geologists, to regard all shells in which no remarkable dif- 

 ference of form and character can be distinguished as inhabited 

 by one and the same genus of animals ; and not less usual to 



• This valuable memoir (from the Philosophical Transactions, Part II. for 

 1835) so interesting to the zoologist, contains also statements of great im- 

 portance to the practical and speculative geologist. SVe, therefore, lay it be- 

 fore our readers without abridgment or alteration.— Edit. 



