PARRBYSIA. 



167 



latere postico corrugatis; deutibus cardinalibus pyraraidatis, 

 lateralibus flexuosis : irapressiouibus musculorum profundis ; 

 margarita albido-incarnata. 



Long. 38, lat. 51. diam. 20 min. 



Hah. Tavoy; also recorded in the Indian Museum from the 

 following Burmese localities: Pegu, Arakan, Tenasserim, and 

 Mandalay, 



Yar. triembolus (Benson). 



Unio triembolus, Benson, .T. A. S. B. xxxv, 1855, p. 44 ; id. A. M. 



N. H. X, 1862, p. 190; II. .^ T., C. I. 1876, p. 4y, pi. 107, fig. i'; 



Paital, Conch. Sam. iii, lf<90, p. 170. ■ o - 



Unio Ao«/;yf/arrt«/r«*', Tapparoue-Cauefri, Ann. Mus. Civ. St. >at. 



Geneva, vii, 1889, p. 341, 



Orujhml description :— A thick shell with large teeth. A massive 

 species which inhabits the jS'erbudda, and the shells of which are 

 fouud fossil associated with the bones of extinct mammalia in the 

 gravels of the river valley, may be a variety of this species 

 [P. tavoi/ensis]. 



The author writing in the ' Annals & Magazine of Natural 

 History,' in 1862, further describes his species. 



Testa oblique rhomboidali, subtrigona, transversa, injequilaterali, 

 crassa, antice brevi rotundata, postice subalata, descendente, 

 demum angulata, obtusa, margine ventrali couvexo : disco trans- 

 verse plicato et striate, piceo-nigrescente ; umbone tumido, gibboso, 

 versus apices remotos obtiisos decorticatos iridescentes radiato- 

 sulcato, carina umbonali obtusa ; dentibus cardinalibus crassissimis, 

 corrugatis, lateralibus obliquis, valva dextne duplicibus, sinistra 

 triplicibus ; margarita albida vel colore salmonis tincta. 



The dimensions of three specimens given at the end of Benson's 

 description are as follows: — 



1. 2. 3. 



Long 47 4.J 44 mm. 



Lat 57 62 63 mm. 



Diam 27 27 30 mm. 



Ilab. Kanigunga, near Moradabad. Specimens in the Indian 

 Museum are labelled Cachar ; Barrack Kiver, Silchar, and 

 Calcutta. 



The author also mentions that he obtained the following 

 variations of this form : — 



(1) Smaller, and more trigonal. Ki\er Goomty. 



(2) Smaller, obli(piely elongated. Eiver Goomty, 



(3) Green and olive in colour. Eiver Dojora, near Bareilly. 



(4) Gibbous, River Gungut. near Monghyr, in Bahar. 



The following note is given with reference to the description of 

 the typical form : — " The anterior and posterior cicatrices are 

 distinct, the latter particularly so; the apical cicatrices are in- 

 distinct on the inner side of the cardinal tooth ; cavity of the 



