PLATE XV. 



-pirrs. ... 1 — 5. LuciN.^. [Myrtea] Arcotina, 5/0/?., p. 258 ; side-, front-, and inner-, views of 



different specimens ; in fig. 1 the upper posterior part of the shell is restored ; 

 1 and 2 are from Olapandy, Arrlaloor yroup ; 3, from near Amloor, Tricki- 

 nopoly grovj) ; 4 and 5, the valves of one specimen broken up in order to see 

 the hinge; from Parally, Oofatoor gronp. 



Figs. ... 6 — 8. LuciNA [Myrtea] dentigeea, SfoL, p. 258; views of different specimens; 

 6 and 8 are from Ohipaudy ; 7, from near Arrialoor, Arrialoor group. 



Pio-. ... 9. Trigonia ventricosa, Krauss, from supposed Jurassic rocks of South Africa 



(vide p. 315). 



Fio-s. ... 10 — 12. Trigonia tuberculifer.\, SfoL, p. 315; 10, front-view drawn from two 

 separate valves; 11, side-view of aright valve; 12, internal view of the 

 hinge of a left valve ; Coonum, Tnchinopoly grcmp. 



Fig. ... 13. Trigonia crenifera, Stol., p. 318 ; side-, and front-, views of a perfect speci- 



men ; Olapaudy, Arrialoor gronp. 



Figs. ... 14 — 15. Trigonia INDICA, iS/oi., p. 315; side-views of both valves and front-view of 

 the left one ; south-east of Arrialoor, Arrialoor group. 



Figs. ... 16—17. Trigonia orientalis, /b/-^/".?, p. 31fi ; 16, inner view of a small left valve; 

 17, side-view of a right valve ; 17 a, front view in which the left valve has 

 been drawn after another specimen ; near Comarapolliam, Arrialoor gronp. 



Figs. 18, 20, 21. Trigonia minuta, Stol., p. 317; side-, front-, and inner-, views of three differ- 

 ent specimens ; near Arrialoor, Arrialoor gronp. 



Figs. 10, 22, 23, 27. Trigonia semiculta, Forbes, p. 317 ; in 27 the outline of the valve is restored 

 from another specimen; 19 is from Mait/ialj the other specimens fiom 

 near Anapaudy, Trichiinpoly group. 



Figs. 24 — 26. Trigonia scabra. Lam., p. 314; 24, 24 a, and 26 are umbonal-, front-, and 



side-, views of the same specimen from near Serdamnngalum ; 25, 25 a, 

 side-, and front-, \'iews of a specimen from Shutamungalum ; the tubercles 

 on the ribs are quite worn off; Tric/iinopoly group. 



