LAND SHELLS OF GENUS OBBA FROM MINDORO 345 



In colour and in the direction of the form and shape of the aperture it bears 

 much resemblance to Helix auriculata, figured by Mr. Swainson (Zoological 

 Illustrations, 1st series) from a specimen formerly in the cabinet of Mr. C. Dubois, 

 afterwards in mine, and now in the British Museum; but in H. auriculata the 

 whorls are comparatively rounded, and the body-whorl is quite round instead 

 of having a sharp edge. //. auriculata is besides, in many individuals, dimpled 

 with small depressions. These differences may be sufficient in the present state 

 of our knowledge to constitute specific distinction; but whether they are in 

 reality strong enough to form such a separation, may well be doubted. My 

 present impression is, that H. auriculata and H. Lisleri are identical; but I shall 

 return to this subject when I have examined the whole of the cognate series in 

 Mr. Cuming's collection. 



Since he here cites Albay, Luzon, as the home of the species, I 

 shall follow this dictum and consider this the habitat for the restricted 

 typical subspecies. I am giving on Plate 88, Figure 5, photographs 

 of three views of a typical specimen from Albay. 



Obba listeri occupies a very wide range in the Philippine Archi- 

 pelago, and, like most widely distributed species, it breaks up into 

 a host of races, each of which occupies a limited zoogeographical 

 horizon. From the Mindoro Province I have no less than nine 

 before me, which I shall designate as subspecies. I believe that this 

 is by no means all the races of this species that will eventually have 

 to be recognized, for there are still a number of small islands within 

 the area under discussion from which no Obbas are as yet known, 

 and even the large island of Mindoro seems inadequately explored 

 as evidenced by the few spots from which material is at hand. The 

 unexplored reaches may therefore properly be expected to yield 

 more members of this species. 



KEY TO THE SUBSPECIES OF OBBA LISTERI 



Last whorl strongly malleated. 



Axial sculpture riblike sibolonensis. 



Axial sculpture not riblike. 



Incised spiral lines of upper surface very strong campoensis. 



Incised spiral lines of upper surface not very strong. 



Shell lenticular halcona. 



Shell not lenticular. 



Shell depressed-helicoid. 



Shell pale and small minor. 



Shell dark and large mayabigana. 



Last whorl not strongly malleated. 

 Last whorl acutely keeled. 



Malleations absent on base smithi . 



Malleations present on base recurvata. 



Last whorl not acutely keeled. 

 Last whorl acutely angled. 



Malleations present on base caloocana. 



Malleations not present on base subpianulata. 



