GASTROCOPTA. 65 



It appears that G. wolfii and perhaps other forms of the 

 servilis group have been confused with the true G. pazi, which 

 appears to belong near G. harhadensis. I have not seen this 

 species. 



Gastrocopta duncana, new species. PL 17, figs. 1, 2. 



The oblong shell tapers slowly from the last whorl to the 

 obtuse apex, the lateral outlines being convex, the diameter 

 nearly equal at the last two whorls. Color translucent cin- 

 namon, the aperture tawny. Surface glossy, very weakly, 

 finely marked with growth lines. The whorls are moderately 

 convex, the last without wave or crest behind the outer lip. 

 The aperture is shortly oval. Peristome reflected, strongly 

 thickened within, the outer lip becoming narrower above, as 

 usual ; the terminations of lip are connected by a rather short, 

 somewhat heavy parietal callus, thin at the edge. Three or 

 four teeth, as follows: angulo-parktal lamella strong, simple 

 and straight. Columellar lamella rather strong, horizontal; 

 lower palatal fold rather strong, entering, the upper-palatal 

 minute and tubercular (often wanting). The summits of the 

 teeth are whitish. 



Length 2.75 mm., diam. above aperture 1.2 mm. ; 51-2 

 whorls. 



Galapagos : Duncan Island, on the south side, from about 

 500 feet to near the summit (Pinchot Exped.) Type 152689 

 A. N. S. P., coll. by Pilsbry and Cleaves, 1929. 



This species differs conspicuously from other Galapagos 

 gastrocopts by the simple^ completely concrescent, angular and 

 parietal lamellsB, the absence of a basal fold, and the small 

 size or absence of the upper-palatal fold. It has some re- 

 semblance to the North American G. quadridens in teeth. 

 There is sometimes a very slight median depression in the 

 crest of the angulo-parietal lamella where the two elements 

 meet, but others do not show this. 



All of the living examples were partly covered with an 

 irregular incrustation of black dirt, differing from G. munita 

 and G. clausa, which are generally clean. The seventeen speci- 

 mens found were picked out of lots of G. clausa, of Avhich 



