70 GASTROCOPTA. 



Man. Conch, vol. 24, pi. 19, figs. 1-3 (munita) and figs. 12-14 

 (clausa), are very readily distinguishable. 



Distribution: Originally described from Indefatigable 

 Island (Theodor Wolf), it was taken on Abingdon by Snod- 

 grass. During the Pinchot Expedition I found it on Chatham, 

 from near shore around Wreck Bay to the lower limit of the 

 grassy zone on the road to Progreso. Charles Island at Post- 

 ofifiee Bay and Black Beach. Barrington Island. Indefatig- 

 able Island at Academy Bay, Seymour Bay and Conway Bay. 

 Duncan Island, from about 500 feet to the summit. Albemarle 

 Island inland from Villamil. The localities are all in the 

 arid zone, except on Chatham and Duncan where it extends 

 to the lower edge of the humid region. It is a very abundant 

 species near shore, around the roots of shrubs and among 

 rocks. 



In many lots there are two main forms: a larger, about 

 2.6 X 1.3 mm., 5 whorls, ovate-conic, the color very light 

 brown, aperture white (PL 17, fig. 10) ; and a smaller form, 

 about 2.1 X 1.0 mm., 4% whorls, cylindric, of a darker color, 

 between cinnamon and cinnamon-brown, the aperture colored 

 (PI. 17, fig. 11). These forms agree in teeth and in having a 

 low crest behind the outer lip. There are some intergrading 

 specimens in both shape and color of shell and aperture ; albino 

 individuals of both forms occur. Those figured are from an 

 aa ridge on the trail between Villamil and San Tomas, Albem- 

 arle, in the arid zone. 



At Academy Bay, Indefatigable Island, small and large 

 forms measure : 2.2 x 1.1 mm. and 2 x 0.95 mm. 



Duncan Island at about 500 feet on the southern side : 2.6 x 

 1.15 mm., 2.2 x 1.15 mm. and 2.2 x 0.95 mm. (PI. 17, figs. 16, 

 17,19). 



In the most fully developed examples of G. claitsa there are 

 no less than eleven teeth (PL 17, fig. 18, a mile inland from 

 Black Beach Road). Usually however, there are nine. 



On Chatham Island back of Wreck Bay typical G. clausa 

 occurs, though the teeth are less strongly developed than in 

 many specimens from islands westward. There are also 

 small brown examples in some of the lots, not often over 2.25 



