DUTCH BORNEO-EXPEDITION. 149 



interior characters. This and the next species seem to be 

 transitional forms between Parmarion and Helicarion *). 



6. Helicarion semicalcareus , n. sp. 

 (Plate 2, fig. 3). 



Shell globose, slightly depressed, only the upper part cal- 

 careous, lower part membranaceous, forming on the limit 

 a slight angle; as the shell of the unique specimen is 

 coherent to the body, its under surface and the form of 

 the aperture are not visible ; upper part smooth, shining, with 

 a few wrinkles; colour golden yellow, except the nucleus 

 which is chalk-white ; spire and suture slightly sunken ; 

 whorls about 2 , very rapidly increasing , nearly the whole 

 shell formed by the last whorl , giving it the character of 

 being a Vitrina ; aperture very large , peristome thin. 



Animal reddish grey, with darker shades on the back; 

 sharply keeled, keel reddish behind; mucous pore with a 

 horn above; shell-lobes with black streaks and spots; 

 moreover a black line runs on the part of the mantle, 

 which borders and covers the peristome. 



Diam. maj. (of shell) 972 1 """i' ''' ™^^^- "~ Length of 

 the animal 21 mill. 



Locality: Top of Mount Liang Koeboeng, March 1894 

 (Büttikofer). 



This species has much puzzled me ; at first sight it looks 

 like a Vitrina but on closer examination I can only iden- 

 tify it with Helicarion. It may be allied to H. Whiteheadi 

 Godwin Austen, as most of the characters of this species 

 can be applied to the specimen before me. Besides other 

 differences, the most striking peculiarity by which it is 

 distinguished from Whiteheadi^ is the membranaceous sub- 

 stance of the infra-peripherical part of the shell. If later on 

 more material of my species and of H. Whiteheadi will 



1) Messrs W. E Colliuge and H. H. Godwin-Austen have lately described two 

 other species of Micro parmarion from Borneo, and have given many anatomical 

 details (Proc. Zool Soc. London, 1895, p. 241; pis. 11—14). 



Notes from the Leyden IMuseiim, "Vol. XVII. 



