OP SOUTHERN INDIA. 83 



Anatinid^ ; in the tertiary period the number rapidly decreases, and of recent there 

 are about eight distinct species upon record. Like all such forms, of which Prof. 

 Forbes says that they belong more to past ages than to the present fauna, they have 

 a wide geographical distribution, being scattered in small numbers oyer the whole 

 world. In addition to the recent genera I shall mention a few fossil (paleozoic and 

 mesozoic) forms, which are more or less closely allied to the former. 



1. Notomya, McCoy, 1847, (Ann. Mag. Nat. Hist., xx, p. 303). Shell trans- 

 versally oval, sub-equivalye, inequilateral, solid, slightly gaping at both ends ; hinge 

 with one strong tooth in the right valve, which appears to correspond to a pit in the 

 left ; the two muscular impressions are large and deep, a third, small accessory 

 one is situated above the anterior large one ; pallial sinus very small, or only in- 

 dicated by a truncation of the pallial line ; ligament strong external. 



This appears to be one of the oldest forms of PanopcF-a, first described from the 

 palaeozoic rocks of N. South Wales. The characters of the genus are not very 

 clearly defined, but from what is now known of these shells it seems impossible to 

 class them in any other family. McCoy appears to me to have been perfectly correct 

 in pointing out the relation of these shells to the IlycB ; and as his characteristic 

 is far more intelligible than that given by Dana of his Mceonia, I think it 

 advisable to accept his name. Great confusion exists among the fossils which 

 have been described from the N. South Wales palaeozoic (carboniferous ?) rocks, and 

 some of the species, described as Notomya or Mceonia, may just as well belong to 

 JPachydomus, and vice versa, 



Dana described ( ? published) a few months earlier than McCoy, several species 

 from N. South Wales under the new generic names of Myonia^ Cleohis, and Fy ramus. 

 In his Geology of the Unit. St. Expl. Exp., vol. x, 1849, p. 694, he accepts only one 

 generic name, McBonia^ and divides this into three sub-genera, Mcsonia, JPyramia^ and 

 Cleobls, of which the author pronounces the second to be identical with Notomya 

 of McCoy. This is a delicate way of dealing with generic names of shells! 

 Neither in the text nor in the atlas does Mr. Dana mention which of the species 

 belong to each of the three sub-genera ; and from the descriptions and the figures 

 the reader will find it very difficult to arrive at anything like accuracy of deter- 

 mination. I have examined several specimens of various species, but I cannot for 

 instance trace a generic distinction between Facliyd. cuneatus and McEonia axinia 

 of Dana. Again, such species, as M(E0. valida and M. grandis or M. gigas, the first 

 of which are strong Crassatella-like, the others thin £[omomya-like shells, very 

 improbably belong to the same genus (even should it be in the Lamarckian sense), 

 but more likely to altogether different families. 



2. Anthracosia, King, 1856, (non 1844), (Ann. Mag. Nat. Hist., xvii, p. 51). 

 Shell oval, equivalve, inequilateral, solid ; hinge with one thick, horizontally elongated 

 tooth in the left valve fitting into a strong excavated tooth of the right valve ; liga- 

 mental fulcra large, corrugated, and situated just above the hinge and below the 

 beaks, somewhat extending posteriorly : Type An. Beaniana, (loc. cit., pi. iv, 



