1918.] B. Peashad : The Anatomij of Indian Mollusca. 147 



Unionidae of Simpson ; the Indian species investigated carry the 

 glochidia in all the four gills (endobranchiae), and will have to be placed 

 in the sub-family Unioninae of Simpson or according to the later classi- 

 fication of Ortmann^ in the restricted sub-family Unioninae, Ortmann. 

 None of the older names being available, the generic name Indonaia is 

 proposed for the Indian species with Unio caeruleus, Lea, as its type. I 

 have as yet been able to examine the animals of /. caerulea, I. caerulea 

 var. gaudichaudi, I. pachysoma and I. pugio. In these the description 

 of the soft parts given below was found to be constant. It is to be 

 expected that the structure of the animal in the other Indian species, 

 hitherto assigned to the genus Nodularia, would be similar, and the 

 genus Indonaia would therefore include all the species described by 

 Preston, loc. cit., pp. 135-146. 



I have nothing to add to the following description of the shell given 

 by Simpson for the group of N. caerulea, " shell elliptical, inflated, 

 pointed about midway up behind, the post basal region produced, with a 

 well developed posterior ridge ; beaks sculptured with numerous fine, 

 radiating riblets, the central ones of which join below, the whole often 

 more or less zigzagged, and extending well over the disk ; epidermis 

 generally bluish-green." 



The animal (fig. 2) may be described as having the inner gills much 

 wider than the outer both in front and behind. The inner lamellae of 

 the inner gills are not free but united with the abdominal sac throughout 

 and with each other behind to the end. The palpi are rather large ; 



O.G. 



Animal of Indonaia caerulea var. gamUclmudi. F.^iooi, I. G. -Inner gill, 0. G.= 

 Outer gill, P. = Palp, S. .4. = supra -anal opening. 



the mantle has the margin simple and not toothed ; the branchial open- 

 ing is large with three to four rows of pointed papillae ; the anal opening 

 smaller than the branchial of a light brown colour without any tubercles ; 

 the supra-anal opening separated from the anal by a distinct mantle 

 connection which is rather short. The supra-anal opening itself is 



Ann. Carnegie Mus. VIII, pp. 223-224 (1911-12). 



