INVERTEBRATE PALiEONTOLOC. V 195 



have to consider an Arcopagia the type of Tellina, if I mistake not. Coming 

 down to later authors, Miiller, in 1776, adopted the name, bul applied it to the 

 fresh-water genus Cyclas (more properly Sphesrium), and perhaps in part to 

 Unio, &c. In 1792, Bruguiere adopted it, but with rather wide limits, his 

 first species being an Arcopagia, Lamarck, however, adopted it in 1789, 

 and the only species cited by him then was T. virgata, Linn., belonging to 

 the section Tellinella. Consequently, it seems to me very probable that 

 this will have to be regarded as the type of the genus ; Lamarck being appar- 

 ently the first after Linnaeus to select any one typical form. In 1801, how- 

 ever, he cited only T. radiata, now most generally considered the typical 

 species. 



This is another genus, the exact geological range of which is very diffi- 

 cult to determine ; the shells being most generally thin, and consequently 

 not easily separated from the matrix so as to expose the hinge-teeth, which 

 are also often so small as to be accurately determined with difficulty in fossil 

 species. A few shells have been referred to Tellina from Palaeozoic rocks, 

 but we may safely conclude that none of them belong to the genus, or 

 probably even to the same family. The same may also be said in regard to 

 the Triassic tellinoid shells. Some species from the Jurassic rocks have 

 more or less the aspect of Tellina; but it is not probable that their hinges 

 and internal characters would be found to agree exactly with this genus as 

 understood by modern conchologists. 



In the Cretaceous, however, we meet with apparently a few true 

 Tellinas, and many species falling into several of the subgenera. The genus 

 increased through the Tertiary epoch, and perhaps attains its greatest numer- 

 ical development in the existing seas ; the subgenus Tellinella being appar- 

 ently more numerous at present than any of the other sections. 



The genus, as represented by the various subgenera, has a world-wide 

 geographical range, but is most abundantly represented in tropical seas, 

 where these shells are often delicately and beautifully tinted. 



Tellina ((Eue!) subscitula, Meek. 

 Plate 2, figs. 11, a, 1>. 

 TelVnia subscitula, Meek (1871), Hayden's Sec. Aun. Report Geological Survey of the Territories, 310. 



Shell small, elliptic-subovate, much compressed; pallial margin forming 

 a regular semi-elliptic curve; extremities narrowly rounded, the posterior 







