OE SOUTHEEN INDIA. 397 



former in the same group. I do not, however, see the propriety of establish- 

 ing a separate family for Vulsella, as has been done by H. and A. Adams, 

 especially since the anatomy of the last-named genus and of Crenatula, made 

 known by Veil Ian t, does not support this classification. 



27. Chalmasia, Stol., 1870. Irregularly oblong, longer than high, with 

 prominent obtuse beaks, sub-equivalve, the valves being slightly convex, liga- 

 mental groove large, moderately excavated, margin in front of the beaks with 

 several irregular incisions, or internal grooves, similar to those of FAigmus, muscular 

 scar sub-central, elongated, and strongly thickened ; type. Vulsella Turonensis, 

 Duj., (an concentrica, Woodw. !) from cretaceous beds. Munier-Chalmas (1. cit., 

 p. 107,) refers this species to Vulsella, but in no recent or tertiary species of 

 that genus do any incisions or plications occur in front of the beaks, nor is the 

 muscular scar equally strong in any of them. The shell differs from JEligmus, 

 merely by its more compressed form and more centrally placed muscular scar and 

 by its thicker shell; it shows greater affinity to Fedum, which has, however, 

 only one incision before the beak, and the ligamental pit strongly produced 

 internally. Beside the type species, two others from cretaceous deposits. Vulsella 

 aviculoides, (seu Larquei),^ and V, pernoides of Coquand, probably belong to 

 this genus, but the descriptions are not sufficient to decide the generic identity of 

 those species. A few others will be mentioned in the list of cretaceous vulsellinm, 



28. Nayadina, Mun.-Chalm., 1862, (Bull. Soc. Linn., Normandie, viii, p. 108). 

 Elongately oval, sub-equivalve, tumid, solid, inequilateral, anteriorly narrowly pro- 

 duced, beaks tumid, obtuse, ligamental pit interior, anteriorly produced, a small 

 tooth in the right valve behind the pit corresponding to a depression in the other 

 valve ; lunular area long, slightly gaping, with simple thickened margins, posterior 

 side shorter, evenly rounded ; muscular scar small, sub-central, semi-lunar, deeply 

 impressed; surface of shell concentrically lamellar; type, N. Heberti, from. cretB.- 

 ceous deposits. This is the only species as yet known ; its form closely approaches 

 that of Eligmus, but is readily distinguished from it by its more solid, lamellar 

 structure and the absence of any incisions in front of the beaks. 



29. JDimya, Rouault, 1850, (Mem. Soc. Geol. de Erance, 2nd. ser., iii, pt. ii, 

 p. 470). Sub-orbicular, inequivalve, valves flattened, — one of them (the left ?) 

 is believed to be adherent, — thin ; beaks small, sub-central, internally with a small 

 triangular cartilage pit in each valve ; a finely denticulate line issues from the 

 beaks and continues all round near the margin, it was evidently produced by the 

 serrated edo'es of the mantle ; muscular scars two, one anterior and one posterior ; 

 the latter is the larger, and both are situated some distance from the margin; 

 pallial line entire; type, 2>. FesJiayesiana, Rouault, from eocene beds at Bos. 

 d'Arros, France. 



This is a very peculiar shell ; its form and structure resembles Flacenta or 

 Flacima, but there are no hinge-teeth present ; the two muscular scars separate, 



* There is no reason to change the specific name when it has been proved that the species is not an Ostrea 

 (vide Coquand Mon. Ostrea, terr. cret., p. 195). 



