140 UN I o INI'RAROSTRATUS. 



NOTE XVII. 

 ON UNIO INFRAROSTRATUS, SCHEPM. 



BY 



M. M. SCHEPMAN. 



(September 1896). 



In Vol. XVII of this periodical (p. 161, pi. 4, fig. 2) I de- 

 scribed and figured as new an Unio , collected by the Zoo- 

 logist of the Dutch Expedition to Central Borneo, under the 

 name of in f rarostratus. Prof, von Martens, whom I sent a 

 copy of my paper, suggested that it might be the same 

 species as U. caudiculatus v. Mart. (Malakozool. Blatter, 1867, 

 p. 16). As this species was not yet figured, and my specimen 

 did not agree in every respect with the description of v. Mar- 

 tens , it was rather easy to make the mistake. Von Martens 

 says: »area postica admarginem in xoBioWum parvulum rectan- 

 gulum procurrente", and, as the figure in my paper shows , 

 the rostrum is rather large. As to the sculpture v. Martens 

 says: » striae concentricae inaequales , ad angulum postico- 

 lateralem in lamellas parvas elevatae'\ Now these lamellae 

 are wanting in the specimen I described: only near the 

 lamellose margin, there is something of the kind. 



Prof. V. Martens had the kindness to send me a photo- 

 graph of a specimen of caudiculatus of 60 mill., thus smaller 

 than my type, and on closely comparing it with my spe- 

 cimen , I find that the differences oiay depend only on age. 

 The outline of the photographed specimen agrees perfectly 

 well with a line of growth of my U. infrarostratus and the 

 lamellae , which seem indeed to be very small, may be rubbed 

 off. So I have no doubt of the identity of the two species, but 

 it may be that, on comparison of more specimens and the 

 differences proving to be constant , my species will have the 

 rank of a variety. In any case, however, the specific name 

 must be caudiculatus v. Martens. 



Notes from the Leyden ]Museum, Vol. XVllI. 



