OF SOUTHERN INDIA. 131 



11. Tellina [Linearia] sculptilis, Stoliczka, PI. V, Figs. 6-7. 



Tell. CLin.) testa ovato-elomjata, sub-mcequilateraU, antice paulo longiori, 

 ad terminationem late rotundata, postice brevlorl, i)aululum angiistiori ac rotundate 

 truncata, mediocriter convexiuscula, concentrice confertim costulata ad tUrumque 

 latus stiHis nonnullis radiatitibiis ornata, strils anticis crassiusculis ; umbonibiis 

 antice versus ineurvis, prommulis ; marguiibus superioribus moderate decUvis, margine 

 inferiori lente curvato. 



This species is as to form closely allied to two others from cretaceous rocks, 

 Lin. concentrica, Reuss, and I/in. semiradiata, d'Orh. The first has the anterior 

 side narrower instead of the posterior, and the second has distinct radiating lines 

 only on the posterior side; thus the form, as above described, and the numerous striae 

 are characteristic distinctions of the Indian fossil. The concentric striae or ribs 

 are rather strong, but very close together, and even on the middle portion of the 

 surface of the shell there are some indications of fine radiating lines. The right 

 valve has an anterior cardinal tooth distinctly bifid, and a posterior, parallel to the 

 margin, prolonged ; the lateral teeth are distant and very distinct. 



Localitij. — Comarapolliam, in a greyish sandstone. 



Formation. — Arrialoor group. 



XII. Family,— B ON A CID^. 



Animals closely resembling those of the Tellinidm, but the siphons usually 

 are shorter, thicker, and with fringed orifices ; the foot is lingui-form, compressed, 

 the palpi and gills of moderate size, one pair on each side. 



The shells are more or less wedge-shaped, transversally elongated, always 

 strong and solid, closed on both ends, the posterior side often shorter, but some 

 species are nearly equilateral, and a few others have the anterior side shorter ; 

 the inner margin of the shell is smooth or crenulated ; the hinge usually has 

 two strong cardinal teeth in the left and one in the right valve ; sometimes 

 there is in the latter a small posterior cardinal tooth traceable ; lateral teeth are 

 two in each valve, those of the left are always smaller than the corresponding 

 ones of the right valve, sometimes those in the left valve altogether disappear, 

 but the right laterals very rarely become obsolete ; the muscular impressions are 

 strong and the pallial sinus deep, extending in the elongated forms like Hecuba, 

 or Iphigenia, horizontally, in Donax and others it is ascending and dilatated ; 

 ligament short, strong, generaiUy supported by thickened fulcra. 



Deshayes was the first to point out some of the characteristic distinctions in 

 the animals and shells of the Do'sacidm and Tellinibm, urging their separation 

 as two distinct families respectively. Formerly the genus Donax was classed 

 with Tellina. H. and A. Adams and others formed a sub-family under the 

 name of donacin^, and there can be no doubt that the latter are very closely allied 

 to the Tellwibm, which is especially the case with regard to some of the forms 



