106 GASTROCOPTA, EASTERN ASIA. 



far forward as the middle of the angular lamella ; inf raparietal 

 lamella long, not quite so deeply placed as the parietal. Colu- 

 mellar lamella strong, horizontal throughout. The palatal 

 and basal plicae stand on a strong callous ridge, the lower 

 palatal being largest, suprapalatal and basal smaller. In the 

 type lot there are one or two minute infrapalatal denticles, 

 between lower palatal and basal. The lip is thin, a little ex- 

 panded, the outer margin somewhat bent in, in the middle, and 

 very strongly arched above. The adnate part of the peristome 

 is very short. Length 2.4, diam. above aperture 1.35 mm. 



Chichi jima, Ogasawara (Bonin) islands (Hirase). Type 

 and cotpyes No. 83897 A. N. S. P. 



Peculiar for the nearly equal length of the three lamellae 

 of the parietal wall, which stand parallel, the angular and 

 parietal being only weakly connected. 



The teeth in the base are variable, some individuals having 

 two denticles between lower palatal and basal, some one, and 

 one example none. The basal and infrapalatal folds are some- 

 times subequal. 



The crest behind the lip is variable, as in American Gastro- 

 coptas of the pentodon group. Usually it is strongly de- 

 veloped, but in one example it is reduced to a very low, broad 

 wave. A small individual measures, length 2.25, diam. 1.3 

 mm., 5 whorls. 



Under a high power, the surface is seen to be densely, 

 irregularly granulose throughout. 



38a. G. c. ogasawarana n. subsp. PL 20, figs. 3, 6. 



The shell is smaller than chichijimana, with the angular and 

 parietal lamellae less widely separated ; basal fold stout, well- 

 developed; no minor folds between it and the lower palatal 

 plica. Aperture of a more triangular shape, the external crest 

 and the internal palatal callous strongly developed. Length 

 1.75, diam. 0.96 mm. 



Ogasawara (Bonin) islands: Chichi jima, type loc. ; Ototo- 

 shima (Hirase). 



Some specimens are intermediate in size between this form 

 and typical chichijimana ; otherwise it would be thought speci- 

 fically distinct. 



