OP SOUTHERN INDIA. 277 



impressions ovate, slightly impressed; hinge uuknown. Type, C. lamellosa, Ilall, 

 from the Lower Helderberg (Silurian) group of North America. 



This is a rather unsatisfactorily known palaeozoic genus ; the shells have the 

 aspect of Trapezium, but appear to be thinner, and nothing is known of their 

 hinge by which their proper classification could be decided. I insert the genus 

 here simply on account of the resemblance which some of the species show to 

 Megalodon on the one and to Cardlnia on the other hand. 



11. Anoplophora, Sandberger, 1862, (vide Alberti's Ueberblick iiber die 

 Trias, 18G1, p. 133). Shell elongated, laterally moderately compressed, inequi- 

 lateral, beaks sub-anterior, hinge with a small indentation, without any per- 

 ceptible cardinal teeth and with very slightly thickened lateral margins on either 

 side ; anterior muscular impression cordiform, enlarged, posterior very faint, liga- 

 ment linear, external. Type, Anop. f Mi/acitesJ fassaensis, Schloth., sp. Most 

 of the species refei-able to this genus occur in the Trias ; they differ from Cardlnia 

 by the want of hinge-teeth, and some forms closely resemble Pleiii'op/ionis, but 

 they appear to have a thinner shell. It is difficult to say what the real distinctions 

 of the present genus are as compared with the former, and possibly they may be 

 identical, at least in part so. 



12. Cardinia, Ag., 1841, (Pictet, Traite dePal., iii, p. 522). Shell trigonal 

 or ovately elongated, compressed, inequilateral, with pointed, not very prominent, 

 beaks, these being close together; hinge with one cardinal tooth in the right 

 and two small ones in the left valve, and one remote lateral tooth on either side 

 in each valve ; muscular impressions deep, rather small, and situated next to 

 the lateral teeth ; ligament of moderate strength, but long. Type, C. conciima. 

 Sow., sp. This genus is sparingly (and rather doubtfully) represented in silurian 

 rocks ; its maximum of development falls in the Lias, and it disappears with the 

 close of the Jurassic period. 



13. Triyonodiis, Sandberger, 1861, (vide Alberti's Ueberblick tiber die 

 Trias, p. 125). Alberti- introduced this name for a few triassic species, of which 

 his T. SandbergetH may be considered the type. The form of the shells is entirely 

 that of Cardinia, and the hinge also appears to be nearly the same, except that 

 the posterior lateral tooth is very strong, single in the right and double in the 

 left valve; the anterior lateral tooth is short and small, the cardinal teeth are 

 distinct ; the muscular impressions elongated and attenuated above. The genus is 

 said to be " totally distinct" from Cardinia, though it certainly does not appear 

 tq be so. 



14. Euloxa, ( ? Conrad, 186 ? Check-list, Miocene foss.. North America, 

 Smiths. Misc. Coll., No. 183, 1864, p. 7). Shell like Astarte, somewhat produced 

 posteriorljs hinge apparently with three cardinal teeth in the left valve, the two 

 teeth on the sides being much smaller thaia the median one, and two teeth in the 

 right valve. The type of this genus seems to be Venus latisulcata, Con., (Mioc. 

 foss., p. 40). I have not met with the original description of Euloxa, and only 

 know it from Meek's reference. 



