404 Records of the Indian Museum. [Vol. XVI 



condylea) vondemhuschiana. H. & A. Adams/ recognizing the 

 validity of d'Orbigny's genus Monocondylea, assigned the species 

 to that genus, lyater Conrad * established a new genus Monodon- 

 tina for the same species,^ abbreviating the specific name also ; 

 but subsequently, considering his new genus to be a synonym of 

 Gould's Pseudodon, he again described the species as P. vondem- 

 huschiana. Simpson {loc. ciL), following Conrad, has included the 

 form in the genus Pseudodon, making it however the type of a 

 distinct group, which included a number of other species. This 

 grouping on the whole is artificial, since widely different species 

 such as P. salvenianus have been included in the group of P. von- 

 demhuschiana. A few other unimportant changes affecting the 

 name of this species are given by Simpson. 



The material from Sumatra has made it possible for me to 

 examine the animal of a form of P. vondemhuschiana , and as a 

 result of this examination I have found it necessary to revive 

 Conrad's genus Monodontina — because the animal of the Sumatran 

 species — a form of the type-species of M onodontina — is ver}^ different 

 from that of the type-species of Pseudodon, namely P. salvenianus. 

 I have also added a few notes on the synonymy of the other 

 species, based on an examination of the collection of the Zoological 

 Survey of India (Indian Museum) and a critical study of the 

 excellent figures in Haas' incomplete monograph* and other 

 available literature. 



Of the species included by Simpson in this group P. ellipticum, 

 P. zollingeri, P. cumingii, P. aeneolus and P. iumidus seem to be 

 related to M. vondemhuschiana, and will probabl}' have to be 

 assigned to Conrad's genus Monodontina. It is, however, impos- 

 sible for me to go further into this question as no specimens of 

 these forms are available. It is also impossible to express 

 an}' opinion as to P. thomsoni, P. camhodjensis and P. nicobari- 

 cus owing to incomplete information, while P. moreleti cannot be 

 included in the genus, for, as is shown in the rather poor figure of 

 the soft parts by Deshayes and Julien {loc. cit.), the animal 

 appears to be very different from that of M. vondemhuschiana. 

 Specimens of P. inoscularis identified as such by Mr. H. B. Preston, 

 and now in the collection of the Zoological Survey of India, are 

 undoubtedly no more than a variety of M. vondemhuschiana, 

 while specimens of P. chaperi also merge very gradually into this 

 species. P. zollingeri, as stated above, is undoubtedly a distinct 

 species, but I do not think that Mousson^ was right in including 

 in it shells which he described as var. angulosa, for this latter is 

 probably nothing more than what I describe below as var. chaperi 



' Gen. Rec. Moll., p. 501 (1858). 



' Proc. Acad. Nat. Sci. Pliiladelpliia, VI, pp. 266-449 ('853). 



■^ Amer. Joiirii. ConcJiology, I, p. 233 (1865). 



* Martini und Chemnitz, Couch. Cab. {ed. Kuster), Uiiio. Owing to the 

 war no further instahnents of this work were received in the Calcutta libraries 

 after page 256 and plate 59 (1910). 



^ Jl/oll. Java, Zurich, p. 96, pi, xvii (1849). 



