1 826.J ^f- Gray on the Genus Hinnita of De France^ &jc, 103^ 



made by the expansions and contractions of the air, and the 

 condensation of the vapour ; but if proper time be taken, the 

 results perhaps will not be sensibly atfected. Should they, 

 however, it might be obviated by immersing this part of the 

 apparatus in a vessel of water of a known temperature. 



Probably a joint in the base B C of the tube, enabling the 

 leg A B to have a vertical circular motion about it, would render 

 the apparatus more practically convenient, by making the com- 

 pression in C D more gradual, and taking away the irregular 

 impetus occasioned with pouring the mercury in at the orifice A. 



The greatest merit of this method is its being so complete 

 within itself. It not only gives the tension of the vapour exclu- 

 sive of any previous determination, and clears the results from 

 the uncertainty of delicate ocular phenomena, but it may be 

 applied to almost any portions of any gases with the same ease 

 and success as to the atmosphere. John Herapath. 



Article IV. :^ 



On a recent Species of the Genus Hinnita of De France, and 

 some Observations on the Shells of the Monomijaires of JLa^ 

 marck. By J. E. Gray, Esq. FGS. 



(To the Editors of the Annals of Philosophy.) 



GENTLEMEN, British Museum, July 15, 1826. 



In the list of species of shells not taken notice of by Lamarck, 

 which was published in a former number of the Annals of Philosophy , 

 1 described as a new species of the genus Lima a shell, of which 

 I had observed an old very much worn specimen, in the British 

 Museum ; having, since that period, observed two specimens of 

 a fossil species, which agreed with all the characters that were 

 peculiar to my Lima 1 gigantea, I therefore was inclined to con- 

 sider them as forming together a distinct genus, and I was 

 farther confirmed in this opinion when I re-examined the other 

 allied genera, for I found, by the assistance that the fossil 

 specimens afforded me, that the recent shell was most probably 

 attached (immediately) to the marine bodies, and that it was 

 certainly much more nearly allied to the genus Spondylas of 

 Linnaeus, than to the genus which I had from the examination of 

 the mutilated recent specimen referred it to. 



Thinking that perhaps the fossil shells had been described, I 

 compared the specimen with the characters and observations 

 which De France has given for his genus Hinnites, which he 

 established for two species of fossil shells, and to which he 

 observes there are no recent species known. I found that it 

 agrees in every particular with his remarks, and therefore I feel 



