OF SOUTHERN INDIA. 119 



the shells resemble externally Gastmna, but are much thinner. IT. and A. Adams 

 ap}ily, according to Morch, the name Homala, which is a corrected name of 

 Agassiz for Omala of Schuhmacher, for which the type T. planata of Linne 

 has been taken, and which is therefore identical with the next sul)-genus. 



8«i. Peroncea, Poli, 1791. Shell oblong, thin, anterior side short, posterior 

 elongated, sub-angular, with a slightly elevated marginal plicature ; ligament in a 

 long deep groove ; lateral teeth obsolete, cardinal elongated, but not very pro- 

 minent. Type T. planata, Linn. 



^n. Metis, H. and A. Adams, 1858. Shell elongately oval, moderately in- 

 flated, anteriorly somewhat produced and rounded, posteriorly truncate, shortened, 

 and more or less plicated ; ligament lai'ge, in a deep groove, fulcra thickened inside ; 

 hinge in the right valve with two diverging teeth ; in the left the middle tooth 

 is distinct, but the anterior is represented only by a thickened margin ; not a 

 trace of lateral teeth ; muscular impressions and pallial sinus large. This genus 

 is very characteristic and considerably different from other TelliucB ; its type is 

 Tell. Meye'ri, Phil., and such foi'ms as T. lacmiosa, Chem., TeJl. spectabilis, and 

 many others of the same type, also appear to belong to it, but I have not seen 

 the last named shell. A species similar to spectahiUs occurs fossil in the tertiary 

 deposits of Bm-ma ; it has the ligament marginal and almost covered by the 

 upper edge. Homes says (Fossile Moll, des Wiener beckens, vol. ii, p. 92,) that 

 he satisfied himself of the identity of the miocene form with the recent one. 

 I have just now no materials for comparison, but as far as I can remember the 

 shell there are some not unimportant diff'erences in the fossil form. In any case 

 the Vienna type is more equilateral than any recent specimen I have seen. 



H. and A. Adams refer to the sub-genus Metis merely the single species 

 Tell. Meyerl, Phil., and quote others like lacmiosa, epjhlpinmn, &c., as a sub- 

 genus of So'obicularia under the name Cap)sa, Bosc. I had no opportunity of ex- 

 amining all the species, but those Avhich I have mentioned and a few others certainly 

 are more allied to the Tellinidm than to Scrobiculabiid/e ; they have the ligament 

 soft or spongy, situ.ated in a deep groove, sometimes merely covered by the free 

 sharp edges of the fulcra, but they have no cartilage proper, at least not separated 

 or lodged in a special cavity. The situation of the ligament is sub-internal, 

 perfectly similar to that of many Lucince. 



9. Mactrotmja, Agassiz, 1812, (see Pict. Pal. Suisse, 3"" ser., p. 151). Shell 

 elongated, equivalve, solid, sub-equilateral, posterior side somewhat longer, upper 

 margins sloping, almost straight, both ends rounded ; hinge-teeth not known 

 (? ? wanting), an oblique internal rilj in front of the beaks ; ligament strong, 

 external. Pictet and Campiche have again introduced Agassiz' genus for 

 the type species M. Couloni, and placed it in the Tellinid.^. The authors have 

 examined specimens wdth the shell, Avhich is very thick, only exhibiting stride of 

 growth ; they correctly conckule that the shell cannot belong to the Anatinid^, 

 wdiich are all of a particularly thin structure. It is not easy to find anywhere 

 else a place for the genus except in the Tellinidm, although no hinge-teeth have 



