OE SOUTHERN INDIA. 135 



Bernardi describes one species, F. JDelesserfi, from the rivers of Guinea. Its form 

 and general character is said to be intermediate between Iphigenia and Cyrena, 

 differing from the latter by its pallia! sinus and the smaller number of hinge- 

 teeth. F. cnrta, Dunker, also from Eastern Africa, is a second species. 



7. Galatea, B r u g., 179 ? Shell sub-trigonal, thick, covered with a strong horny 

 epidermis ; hinge with two cardinal teeth in the right and three in the left valve, 

 all much elongated, lateral teeth two in each valve, pallial sinus deep. The species 

 are from the Nile and the rivers of Western Africa. Bernardi examined the animal, 

 and he states that it is more allied to Donax\hsxx to Cyrena. T. Prime gives a list 

 of thii-teen species of Galatea {vide Proc. Acad. Nat. Sc, Phil., 1861, p. 25). 



Deshayes suggests that Sunetta^=Meroe also probably belongs to the Donacwje. 

 There is no doubt that if we compare the general character of the shell of such 

 species as S. Solandri, Gray, with its thick olivaceous epidermis, we are strongly 

 reminded of its great similarity with Iphigenia, but in this as in all other species of 

 Simetta the hinge possesses three cardinal teeth in each valve and one anterior lateral. 

 Such arrangement entirely agrees with typical Venesid^, and I would, therefore, 

 prefer, from analogy of the shells, the classification of Sunetta nest to the fossil 

 Gvateloupia. I hope shortly to be able to return to this question, as soon as I shall 

 have an opportunity of examining the animals of some of our eastern species, for up 

 to the present time the animal of Simetta is not known. A peculiar form of Simetta 

 identical or veiy similar to Solandri, Gray, appears to be common on the Bombay 

 coast. 



I have already remarked that the first forms allied to JDonacibjb appear in the 

 Trias ; there are at least no species from palaeozoic rocks which, even from external 

 resemblance, could be referred to that family. In the Lias we have full evidence 

 of the occurrence of Tancredia (or RettangiaJ ; and next comes Isodonta from 

 jm*assic beds; true Donaces first appear in the cretaceous period, and their number 

 very gradually and sparingly increases until the present time at which the family 

 obtains the greatest development. Sower by, in his most recent monograph of the 

 genus Bonax (Thesavir. iii), describes 65 species ; including those of the other genera 

 and later additions, there are about one hundred species known, distributed all 

 over the temperate and tropical seas, being, however, as usually, more numerous 

 in the latter. Of the tertiary species there are no more than about 22 species on 

 record, and of these the larger number belongs to the eocene fauna of the Pans 

 basin, if really all the species prove to be distinct. 



Erom cretaceous rocks I have but little to mention besides the Tancredia 

 americana, M. and llayd., already alluded to. M. Coquand (Pal. de Const., 

 pi. vi, fig. 18,) described a species as D. Loryi ; the shell may belong to the 

 sub-genus Capsella, Gray, but it may equally well be a Iloera (Tellinib^J, or 

 even a Saxicava. Gabb describes Bonax latm from the Tejon group of California, 

 (Pal. Calif, ii, p. 183, &c.). Other species noted as Bonax from cretaceous rocks 

 have been shown to belong to different genera. I am acquainted with a single 

 specimen from our South Indian cretaceous rocks ; it appears to be a true Bonax, 



