PHILIPPINE LAND MOLLUSKS OF GENUS OPISTHOPORUS 325 

 OPISTHOPORUS QUADRASI QUADRASI Crosse 



Plate 81, Figure 4 



1888. Opisthoporus quadrasi (Crosse) Hidalgo. Journ. Conch., vol. .36. pp. 59, 



60, pi. 5, figs. 6, 6a, 61). 



1889. Opisthoporus quadrasi Dohrn, Nachrichtsbl. Deutschen Malak. Ges., p. 55, 



in part. 



1896. Opisthoporus quadrasi Elera, Catalogo sisteniatico fauna Filipinas, vol. 3, 



p. 689, in part. 



1897. Opisthoporus quadrasi Kobelt and Mollendorff, Nachrichtsbl. Deut- 



schen Malak. Ges., vol. 29, p. 119. in part. 



1898. Opisthoporus quadrasi Mollendorff, Abh. Naturf. Ges. Gorlitz, vol. 22, 



p. 185, in part. 



Shell small, moderately thick, depressed helicoid, yellowish horn 

 colored. All but the first one and one-half whorls are marked with 

 numerous fulgurations of brown on the upper side, which are a little 

 wider than the light areas separating them. These fulgurations 

 extend almost to the peristome. The upper surface, except the smooth 

 nuclear portion, is marked by closely spaced incremental threads and 

 almost obsolete incised spiral lines. The siphon is about 4 mm behind 

 the peristome. It points forward and is marked by rather coarse 

 annulations. Periphery well rounded. Base with an open funnel- 

 shaped umbilicus, showing all the whorls within, with the sculpture 

 a little finer than that of the upper surface. Operculum with eight 

 spiral lamellae, which are marked by oblique raised threads. The 

 depressed center of the operculum is smooth. 



The specimen described and figured (U.S.N.M. No. 303075) comes 

 from the type locality, Balabac Island. It has 4.4 whorls, and 

 measures: Height, 7.8 mm; greater diameter. 14.7 mm; lesser diam- 

 eter, 11.3 mm. 



Remarks. — The Balabac species resembles Opisthoporus quadrasi 

 turturiiKjanus most nearly in size, but it differs in being more eleva- 

 ted, in having the whorls more inflated, in being less openly umbili- 

 cated, and in being fulgurated on the upper surface. The sculpture, 

 too, is finer. 



OPISTHOPORUS QUADRASI BUSUANGENSIS, new subspecies 



Plate 81, Figure 3 



1896. Opisthoporus quadrasi Elera, Catalogo sisteniatico fauna Filipinas. vol.3. 



p. 689, in part. 



1897. Opisthoporus quadrasi Kobelt and Mollendorff. Nachrichtsbl. Deutschen 



Malak. Ges., vol. 29, p. 119, in part. 

 189S. Opisthoporus quadrasi Mollendorff, Abh. Naturf. Ges. Gurlitz, vol. 22, 

 p. 185, in part. 



Shell moderately large, thin, depressed helicoid. The first one-half 

 turn light horn colored, the succeeding two dark chestnut-brown, 



