38 BULLETIN 192, UNITED STATES NATIONAL MUSEUM 



CHONDROPOMA (CHONDBOPOMEI.I.A) MAGNIFICUM ('Sall6' Pfeiffer) 



Plate 8, Figure 7 

 1854. Cydostoma (Chondropoma) magnificiim (Salle) Pfeiffer, Proc. Zool. Soc. 



London, 1852, p. 142, pi. 13, fig. 3. 

 1854. Cydostoma magnificum Pfeiffer, Martini-Chemnitz Conchylien Cabinet, ed. 



2, vol. 1, sect. 19, pp. 365-366, pi. 47, figs. 20-22. 

 1920. Chondropoma (Chondropomium) magnifica Henderson and Bartsch, Proc. 



U. S. Nat. Mus., vol. 58, p. 60. 

 1932. Chondropoma (Chrondopomella) magnificmn Bartsch, Proc. U. S. Nat. 



Mus., vol. 81, art. 6, p. 3. 



Shell broadly ovate, with flesh-colored ground and interrupted axial 

 bands of brown, which also have a spiral arrangement. The submedian 

 band is made up of arrow-shaped markings in which the arrows point 

 backward. A subperipheral band forms a continuous line. The base is 

 also marked by brown spiral lines. Nuclear whorls decollated. Post- 

 nuclear whorls narrowly, tabulatedly shouldered at the summit, and 

 slightly constricted immediately below this, marked by rather retractively 

 slanting, distantly spaced, slender axial riblets, of which 174 occur upon 

 the last turn. Fifty of these are crowded upon the expanded outer lip 

 and the space about equivalent to this behind it. These ribs render the 

 tabulated shoulder slightly crenulated. Periphery of the last whorl 

 rounded. Base inflated, strongly rounded, openly broadly umbilicated, 

 marked by eight poorly developed and rather distantly spaced spiral 

 cords, while on the umbilical wall there are ten additional spiral cords 

 which are much stronger than those on the rest of the base. Aperture 

 large, broadly oval ; peristome double, the outer very broadly expanded 

 and decidedly reflected, the reflected portion marked with numerous 

 concentric lines of growth; the expanded peristome is of almost the 

 same width all around except on the parietal wall, where it is much 

 narrower, giving the peristome the impression of being decidedly notched. 

 The expanded outer peristome is not all in one plane, but the part at 

 the posterior angle is slightly bent forward to form a somewhat earlike 

 element, while the part over the umbilicus is pressed in, to cover this by 

 two-thirds, thus rendering the expanded portion of the inner lip of the 

 peristome decidedly sinuous; the expanded outer peristome shows the 

 colored bands as alternate zones of flesh-color and brown. The inner 

 peristome is only slightly expanded; it is reflected over and fused with 

 the outer. 



The specimen described and figured (U.S.N.M. No. 354983) has 4.3 

 whorls and measures: Length, 15.3 mm.; greater diameter, 19.4 mm.; 

 lesser diameter, 15.5 mm. We have not seen the operculum, but Pfeiffer 

 states that it is typically chondropomoid. 



H. Crosse^^ states that Salle collected the type on rocks at the en- 



« Journ. Conchyl., vol. 38, p. 296, 1890. 



