OP SOUTHEEN INDIA. 257 



Pig. 13, pi. xiii, represents a fourth variety, which in form closely resembles 

 the last, but the thickness is more than one-half the length of the shell, being 

 especially great near the margins. 



I was first much inclined to regard some of these varieties as distinct species, 

 but a careful comparison of the specimens shows that the difterent forms are closely 

 connected with each other, and no doubt all represent one and the same specific 

 type of shell. 



Localities, — All the specimens were obtained from a dark brown earthy lime- 

 stone near Moraviatoor, except a single specimen, figured on pi. xiii, fig. 17, which 

 is from the white limestone near Ninnyoor. 



Formation, — Ootatoor and Arrialoor groups. 



3. LuciNA UNDATA, Stoliczka, PI. XIII, Pig. 14. 



L, testa quadrangulari, 07^biculata, fere csquilaterali, moderate convexiuscula, 

 umbonibus tumidulis, incurvis, acutiusculis et carina obtusiuscula ab umbonibus ad 

 marginem postero-inferiorem decurrente instructa ; superficie st^^iis incrementi minu- 

 tissimis sub-obsoletis tecta ; lunula hand profimda ; ligamento in excavatione brevi 

 pone umbones sito. 



Height of shell equal to its length. 



Thickness „ : its length ... ... ... .,, 0"55 



The only figured specimen I have seen of this shell does not show the hinge- 

 teeth, but judging from external characters it seems to be a Lucina, for the 

 structure appears to be a little too solid for a Mysia C=DiplodontaJ ; still a careful 

 comparison of well preserved specimens with the last named genus would be very 

 desirable. The striae of growth on the surface are almost obsolete ; the somewhat 

 squarish orbicular form with a posterior plicature and the want of a distinct lunula 

 readily distinguish this from the last species. 



Locality, — South-east of Arrialoor, in a whitish sandstone. 



Formation, — Arrialoor group. 



4. LuciNA [cYCLAs] T^NiOLATA, StoUczka, PI. XIII, Pig. 9. 



L. \^Cycl,'\ testa fere orbiculata, parvula, tenui, paulo convexiuscula, superficie 

 nonnullis lineis impressis incrementi ac striis lamelliformibus confer tissimis per 

 longitudinem leviter flexuose percurrentibtis ornata; margine lunulari paulo incurvo, 

 lunula angusta, elongata, mediocriter profunda, haud distincter circumscripta; 

 impressionibus muscularibus regularibus, — dentes cardinis non vidi. 



Height of shell : its length ... ... ^^ q.q^ 



Thickness^* „ : „ ... ... ,,_ ^ q.^^^ 



This is one of the very few species from cretaceous rocks belonging to the 

 sub-genus Cyclas, characterized by its comparatively thin shell and longitudinal 



* In fig. 95 on pi. xiii the shell is shown to be more compressed than it actually is; the convexity of the valves 

 should he appreciably stronger. 



