OF SOUTHERN INDIA. 217 



posterior angle of tlie periphery ; the surface is ornamented by numerous (35-iO) 

 closely set radiating ribs, which are only very slightly tuberculatcd ; in some 

 specimens they appear almost smooth. The short hinge-line characterizes this form 

 as a TmchycanVmm. 



Wheu the surface of the shell is Avorn oif the ribs sometimes become bifid, 

 but their abnormal state is readily traced. 



Localities. — South-east of Arrialoor and at Olapaudy; very common at the 

 former in a light coloured soft sandstone ; the largest specimen measures about 

 40 m.m. in height. 



Formation. — Arrialoor group. 



3. Card. [Trachycardium] productum, Soioerhij, PL XI, Figs. 15-16. 



1832. C. productum, Sow., Traus., Geol. Soc. London, iii, p. 417, pi. 39, fig. 15. 



1865. idem apud Zittel, Deuksch. Akad., Wieu, xxiv, pt. 2, p. 140, pi. 5, fig. 4, — cum st/non. 



Track, testa crassa, valcle inflata, suh-qnadrangulari, altiore quam longa, 

 margine antico ac postico fere parallelis, infero coiwexiusculo, verticibus vahle 'pro- 

 minentibiis et incurvatis. Sitperficie costis radiantibiis numerosis ad medium leviter 

 fiircatis unilateraliter spinulose tuberculatis sulcis angustis disjunctis instructa ; area 

 cardinali ciirvata, dentibus lateralibtis ab cardinalibus moderate remotis, omninis 

 crassis. 



Height of shoU : it.< loiigth ... ... ... ,,. 1-25 



Thicknes.ii „ : ,. ... ... ... ... 0-98 



This species is so well known that it is unnecessary to add anything to the 

 above description. The statement, however, that not the ribs but the intervening 

 sulci are spinulose or tuberculatcd rests, I believe, upon a mistake. The fact seems 

 to me that the tubercles or spines are situated only on one side of the ribs, reaching 

 doAvn to the base of the adjoining fm'row, and pointing either towards the anterior 

 or the posterior end. When the sm'face of the shell is someAvhat eroded the 

 tubercles very easily wear off on the ribs, but they remain preserved in the adjoining 

 furrows, thus giving the impression that they were originally and solely situated iu 

 them. A perfectly similar case can be observed on the recent Card. [ Trach//cardium] 

 elongatum. Sow. 



The species occurs from the Cenomanieu up to the Senouien beds, almost 

 throughout Europe, in Germany, Belgium, France, and throughout the Alpine 

 Gosau deposits ; it is one of the cosmopolitan species, like Protocardium hillammi. 



Localitij. — Kolotui'e, in a bro\Miish calcareous sandstone; apparently rare. 



Formation . — Ootatoor group. 



3g 



