NO. nil. PROCEEDINGS OF THE NATIONAL MUSEUM. 361 



present a special aspect rather unusual among species of tbis genus. 

 The subsplierical or bulb-like protoconcli with which the shell begins, 

 and which is formed within the Oi^g,, when the coiling of the whorls 

 commences, is tipped over and obliquely infolded by the first gyration; 

 a section shows more of the protoconch below than above the first 

 sutural line. The coiling whorl is often strongly keeled on the shoulder, 

 so that from the keel toward the suture is a straight downward slope, 

 while the external surface from the keel toward the periphery is rounded. 

 The circular sweep of the keeled first whorl thus forms an apical funic- 

 ular depression where the point of the spire usually is. In those cases 

 where the first whorl is not keeled it nevertheless shows a dimple or 

 pit at the apex, though not so sharply emphasized. The first 1^ or 2 

 whorls are regularly ribbed with small, distinct, even ribs and about 

 equal interspaces, directed vertically or i)arallel with the axis. Beyond 

 this point the ribs fade and are represented by oblique more or less 

 flexuous elevated incremental lines, often granulated by the crossing of 

 about equally strong spiral strife with equal interspaces. This granu- 

 lation is often inconstant; some of the species may show it well devel- 

 oped over the whole shell, or may be almost free from it, though there 

 are some which are always smooth or even polished, and others which 

 are not known without a well-marked granulation. In strongly granu- 

 lated perfect shells (and markedly in B. artemesia) the granules, or 

 certain rows of them, are regularly tipped with projecting points of 

 epidermis which are very deciduous. The surface shown by Cooper's^ 

 figure 26 as belonging to B. montezuma is an eroded surface and bears 

 no resemblance to the granulation exhibited by an unworn specimen. 

 Figures 29 and 30, on the other hand, are very good and give an excellent 

 idea of the surface of the respective species. 



Now, the peculiar apex and surface above described are exhibited 

 perfectly bj^ B. artemesia ^vhen in j)erfect and well developed condition, 

 but it should be noted that the ribbing of the nepionic whorls is easily 

 removed by wear; and a worn specimen, even when living, may have 

 much of it lost and the worn area polished, almost as if it never had 

 been ribbed. The granulation of the latter surface (as already men- 

 tioned), though always existent, is inconstant in strength and distribu- 

 tion. The granules begin to erode before the rest of the shell, owing to 

 their prominence, and hence in worn specimens their places are often 

 occupied by rows of punctures caused by erosion". 



The peristome is usually thickened and the outer lip but little reflected. 

 The pillar in all the specimens I have seen is nearly straight and in 

 none of them is the axis in the least pervious. Behind the reflected 

 pillar lip is a chink or umbilical fissure which varies in size in differ- 

 ent individuals. The last whorl is often peripherally appressed and 

 usually a little attenuated in front, features greatly exaggerated in 

 '■'■ Columnar ramentosa. Now, Dr. Cooper tells us that his '■'■ Columna''^ 



' Cooxjer, Proc. Cal. Acad. Sci., 2 ser., V, No. 4, pi. vi. 



