OF SOUTHERN INDIA. 433 



Similar differences also apply in a comparison with other allied species, as for 

 instance, P. Diijanliiii, Erem., rarisjplnus, Eeuss, and one or two others des- 

 cribed by Goldfuss. 



The ornamentation of asperuUnus is, however, very variable on account of the 

 scales being easily broken off. The median tubercles are often quite worn away, 

 and the lateral ribs become more or less indistinct, except the two lowest (comp. 

 fig. 10 on pi. xxxi), which are seated in the cavity between the ribs. 



Localities. — Near Kaudoor, in a white conglomeratic sandstone, and near Choka- 

 uadapooram, in a whitish soft limestone. 



'Formation. — Arrialoor group. 



It deserves to be noticed that in the Ootatoor limestone at Cooticaud there 

 occurs another still larger species, probably belonging to the sub-genus Chlamijs. 

 It is apparently a little higher than Pecteu depressiis, Mlinst., (Goldfuss, Petrtef. 

 Germ., pt. ii, p. 53, pi. 92, fig. 4). The ribs are broad, carinate in the middle, 

 with a few radiating strire at the sides, and one more distinct in the groove separ- 

 ating each two large ribs. None of the specimens are, however, sufficiently perfect 

 to define the exact form of this interesting species. 



6. Pecten [Camptoxectes] curvatus, Geinitz, PL XXXI, Figs. 15 — 16. 



PI. XLI, Figs. 4— G. 



1827. .'' Pecteii arcuatus, Sow., apud Nilssoii, Petrif. Suec, p. 22, pi. ix, fig. 14, iion idem Sowerb}'. 



1843. ,, ciirvatus, Geinitz, Kieslingsw., p. 1(3, pi. iii, fig. 13; et 1848, Quadersandst., p. 180. 



1843. „ i>uv/«^«s, Nilss., apud d'Orbigny, Pal. fran?. ten-, cret., iii, p. 602, pi. 434, figs. 7-10, noii 



virr/aiiis, Nilsson. 

 1846. „ virf/aliis, Nilss., apud Foi'bes, Trans., Geol. Soc, Lond., vii, p. 154, pi. xv, fig. 22. 



1840. „ arcuatus, et ? divaricatus apud Eeuss, Ba'hm. Kreidcf., pt. ii, pp.27 and 28, pi, xxxix, 



figs. 6 and 7. 

 1850. „ suhvin/atus, d'Orbigny, Prod., II, p. 253. 



18C6. „ virgatus, Nilss., apud Zittel, Denksch. Acad., Wien, xxv, pt. ii, p. 109, pi. xvii, fig. 8, (baud 



syuon. omnibus). 



P. [ Cainp.^ testa sub-orbictilare ovata, prope apicem sensini angustata, sub-cequi- 

 valvi, valva sinistra paululum convexiore, utraque radiatim confertissime striato- 

 costellata, costelUs depressis, in valva dextra temiioribus quam in sinistra, excurvatis, 

 plurime dicJtotomls, lineis impressis multo angustioribus, p)wictatis, sejxiratis, et striis 

 incrementi concentricis minntis intersectis ; auricidis radiatim striatis aid costellatis, 

 incBqiialibns, postica minore, oblique triincata, antica majore, in val. dextra ad basin 

 profunde insinuata. 



The right valve is in this species always somewhat flatter, and the radiating stride 

 are, as a rule, finer on it than on the left valve ; the ears are marked with oblique 

 transverse stria?, which become on the anterior ear of the right valve mostly obsolete, 

 being replaced by concentric arcuate striae. Zittel published a few years ago a 

 long account of the synonymy of Fecten virgatus, Nils son, but his discrimination 

 of the various forms does not seem to be always correct. I shall briefly notice the 

 history of the present species and of virgatus. 



5 o 



