NO. nil. PROCEEDINGS OF THE NATIONAL MVSEUM. 345 



lamellae, one basal, one parietal, and one on tlie outer Avail of the whorl 

 less strongly developed. An examination of the anatomy by the 

 authors cited shows that the grouj) is related more closely to the Ptipidce 

 than to Cylindrella with which it was originally associated. The first 

 information as to the internal characters of Holospira was given by 

 Bland, ^ who pointed out that H. goldfussii, Menke, beside the ridge visi- 

 ble in the upper part of the throat of the aperture, possesses in the penul- 

 timate whorl four lamelhe ; one very prominent descending from the roof 

 of the whorl for half a gyration; a less prominent one arising from the 

 floor of the whorl opposite the first; a third, more feeble, projecting 

 inwardly from the outer wall, and a fourth revolving on the pillar, but 

 obsolete on the axis above the penultimate whorl. These lamelliie are 

 figured by Strebel and Pfeffer.^ The axis in Holoi-ipira is tubular and 

 under magnification is seen to be vertically streaked with opaque white 

 and translucent markings. In the more slender species like H. gonio- 

 stoma, Pfeiffer, the tube is quite slender; in those which have a shell more 

 stout and clublike, e. g., H. elizabetha', Pilsbry, the axis is wide and 

 spindle-shaped, but in all the base of the adult shell has the axis closed 

 and the umbilicus represented by an impervious chink. 



The angulation of the terminal part of the last whorl varies in the 

 different species, some of which have a keel above and others show one 

 below, the aperture may be subcircular, subtriangular or subquadrate, 

 and may or may not be provided with a columellar or parietal ridge 

 running inward and usually not very prominent. From this ridge the 

 internal lamelhe are entirely distinct. 



An examination of the internal characters shows that the group is 

 naturally divided into sections which may possess any or none of the 

 lamelhe referred to, and that these characters appear to be constant 

 and invariable within the species. By sacrificing the integrity even of 

 single specimens, when the collection contained but one of a species, I 

 have been able to determine the characters of a large number of forms. 

 I find the following to be destitute of any armature upon the pillar and 

 of any internal lamelhe, and therefore to be referable to the subgenus 

 ]\[et((st()ma, Strebel and Pfelfer, of which R. roemeri, Pfeiffer, is the 

 type: II. roemeri, Pfeitfer, II. 2)((sonis, Dall, H. coahuiJensis, W. G. Bin- 

 ney, H. tenuiscuJpta, Stearns, H. pfeifferl, Menke, and H. remondi, 

 Gabb, the first-mentioned si)ecies having the tubular axis exceptionally 

 large. To these I am now able to add two new species ff. crossei, 

 Dall, and H. pilsbryi, Dall, which last has existed in our collection for 

 a long time under the erroneous name of H. fryoni, Pfeifter. The latter 

 species has been examined by Strebel and Pfeft'er and is shown by them 

 from authentic si)ecimens to have entirely different internal characters. 

 They have proposed for it the sectional name of Bostrichocentruni, 

 characterized by having a spiral ridge around the axis extending from 



1 Ann. Lye. Nat. Hist., N. Y., VIII, p. 160, 1865. 

 opiate XIV, fig. 17B. 



