OF SOUTHEKX INDIA. 257 



Fig. 13, pi. xiii, rcjiresents a fourth variety, which in form closely resembles 

 the last, but the thickuess is more than one-half the IcDgtli of the shell, being 

 especially great near the margins. 



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

 but a careful edmjDarison of the specimens shows that the different 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. Llcina undata, Stoliczka, PL XIII, Fig. 11. 



L. testa, quadrangnlari, orbiculata, fere cequilaterali, moderate convexiusciila, 

 innboi'ibiis tumidiilis, incurvis, acutiusculis et carina ohtasiuscula ah umhonihiis ad 

 maryinem postero-inferiorem decurrente instructa ; sttperficie striis incrementi minu- 

 tissiinis sub-obsoletis tecta ; lunula haudprqfanda; ligamento in excavatione brevi 

 pone u)iibones 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 

 structvire appears to be a little too solid for a Ilysia f^DiplodontaJ ; still a careful 

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

 desirable. The strise 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 Ai-rialoor, in a whitish sandstone. 



Formation. — Arrialoor group. 



4. Lucina [cyclas] t.^niolata, Stoliczka, PL XIII, Fig. 9. 



L. [_Cycl.^ testa fere orbiculata, parvula, tenui, paulo convexiusciila, superficie 

 nonmdlis lineis impressis incrementi ac striis lamelliformibus confertissimis per 

 longitudinein leviter flexiiose percm'rentibus ornata ; margine lunulari paulo incurvo, 

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

 iinpressionibus tnuscidaribus regularibus, — denies cardinis non vidi. 



Height of shell : its length ... ... ... ... 94 



Thickness* „ : „ ... ... ... ... 030 



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

 sub-genus Cyclas, characterized by its compai'atively thin shell and longitudinal 



* In fig. 96 on pi. xiii the shell is sliuwu to be more compressed than it actually is ; the convexity of the valves 

 should be appreciably stronger. 



