OP SOUTHERN INDIA. 121 



but not many have as yet been with sufScieut certainty proved to belon"> to that 

 genus. Deshayes' Capsa minima may rather be a Psammocola or JPsammobella, but 

 it has not at all the appearance of a recent Cctpsa. There are also a few species 

 from cretaceous deposits somewhat resembling- Capsa, but those from older forma- 

 tions are very doubtful ; most of the fossil species are without radiating striee, and 

 their relations to Gastrana have in many cases yet to be fully ascertained. 



14.. Liicinopsis, Eorb. and Hanley, 1848, (Mijsia apnd Gray, Lejonkairia, 

 Desh). Shell sub-orbicular, rather compressed, thin, surface concentrically and often 

 also radiately striated ; hinge with two cardinal teeth in the right and three in the 

 left valve ; pallial sinus deep, ascending. L. undata, Penn., may be considered as 

 the type of this genus. The shell has externally a very great resemblance to some 

 DosiNiiN^, especially CycUna, and also to the fossil species which Conrad called 

 Cyprimeria, as well as to dementia in its structure, but according to Clark the 

 animal is quite similar to that of other Tellince. The one bifid tooth in the left 

 valve certainly greatly recalls TelUiia. 



Considering fossil evidence the Tellinid.s do not appear to be so old as many 

 other apparently more highly organised Pelecypoda, for instance, the Anatinid^. 

 With the exception of a few doubtful forms which I stated to have occasionally been 

 referred to TelUnites, and a few others called Psammohia f= GariJ, we have no 

 certain proof of their occurrence in palteozoic rocks. As regards species from 

 triassic and Jurassic deposits hardly any different assertion could be made : 

 there are more forms which resemble garin^ than tellinin^, but I am rather 

 in doubt whether many of those species belong to Gari ; they are, as already alluded 

 to, more probably referable to some of the compressed forms of tafesinje. 



In the cretaceous rocks we have several well marked types, representing a good 

 number of the genera and sub-genera of tellwinm, but I do not know whether the 

 same could be said as regards the oarinm. I have not met with a single species 

 which I could with suflQ.cient certainty refer to Gari (Psammohia), and so far as 

 I know all the other determinations are simply based vipon the external resemblance 

 of the shells. Among these, forms resembling Psammocola and Psammohella 

 mostly occur. With regard to the cretaceous tellininje proper some of the sub- 

 generic types of Tellina, which are at present less numerous than others, were 

 then more prevalent, such as Mcei'a, Zinearia, Angulus and JSomalina ; some like 

 Pal(Bomoera appear to be peculiar to this formation, while others like Peronceo- 

 derma, Tellinella, and Arcopagia are more rarely rejoresented. 



In tertiary deposits we already meet with a fauna greatly resembling the pre- 

 sent one in generic types, but not nearly so numerous in species. Large additions 

 to this fauna have to be expected from the examination of the tertiary deposits of 

 India, and no doubt also of other tropical countries. The miocene species of the 

 European deposits very much resemble those now to be found recent in tropical 

 countries, and several species are identical. What results the tropical miocene 

 fauna will give remain yet to be shown. 



2g 



