FOSSIL GENERA of the SUB-HIMALAYAS. 



56 



fresh-water species ; they are not abundant and are generally in a bad 

 state of preservation. The red marl is with difficulty disengaged from the 

 specimens, any attempt to separate the shell from the matrix being usually 

 at the expense of the epidermis, and too frequently at that of the valves 

 themselves. 



The varieties are few in number, but the determination of fossil species 

 requires so much experience and nice discrimination that no apology will 

 be requisite to excuse silence on this interesting point. A selection which 

 is to be placed at the Society's disposal, will it is hoped afford the means 

 of determining the question.* The univalves bear a small portion to the 

 bivalves, being on the ratio of 1 to 1 00 ; it must however be remarked that 

 the quantity hitherto collected being small, the above proportion might be 

 materially affected by an inconsiderable increase to the number of spe- 

 cimens. 



The same remark is applicable to the result deduced from the number 

 of upper and lower jaws, or portion of jaws at present in the collection; 

 the proportion of the proboscidia to the pachydermata, properly so called, 

 is in the ratio of 3 to 1 — that of the proboscidia to the ruminantia, 5 to 1 . 

 Both proportions may be expected to vary considerably in the course of 

 future researches. 



Many of the specimens have undergone fracture since they were 

 imbedded in their present matrix ; some are much distorted ; and a few are 

 crushed. The Hippopotamus' upper jaws have in consequence of their 

 shape, been frequent sufferers : out of eight upper jaws more or less com- 

 plete scarcely can two be called straight ; the remainder are crooked. Illus 

 trative of the effect produced on some of the relics is the sketch fig. 11, 

 PI. VII. This horn evidently must have undergone fracture when imbedded ; 



* Some of them are figured in PI. XLVIII. figs. 45, 46, 47, 48 of the Journal of the 

 Asiatic Society, vol. IV. They resemble precisely the shells transmitted from theProme fossil 

 field in Ava, by Lieut.-Colonel Burn£Y. Sec. 



