124 PROCEEDINGS OF THE ACADEMY OF [Feb., 



is always coarse on the cone, but on the cylindric part it may be coarse, 

 partially effaced, or fine, in specimens of the same colony, while in 

 some other colonies one or other of these conditions may be developed 

 separately. The White Tail series deserves far more study than we 

 have been able to find time for. 



The shell differs from H. cionella by the perceptibly longer taper 

 and coarser striation of the terminal cone, and slightly greater develop- 

 ment of the basal crest. In the form selected as type (pi. XIII, fig. 3) 

 the ribs continue throughout, but in many examples of the same lot 

 they weaken more or less on the penultimate and next earlier whorls. 

 The callus within the aperture is very heavy. 



Type locality on the south side of the "box" of White Tail Canyon. 

 Types (pi. XIII, fig. 3,) No. 99,684 A. N. S. P. It also was taken 

 at Stations 1, 2, 3, 4, 5, 8, 14; most or all of these colonies being of 

 considerable extent, although' the gathering in each case was made 

 in a small area. The highest points are at Stations 1, 3 and 8; the 

 lowest in the Box Canyon and between Stations 14 and 13. See map 

 on p. 75. It was taken also in Jhu Canyon, Turkey Creek and Time- 

 stone Mountain. All of these stations are on limestone. 



There is variation in sculpture in the type colony, some examples 

 being strongly striate throughout, but in most the striae are weaker 

 on the penult whorl. PI. XIII, figs. 3, 4 and 5, represent shells from 

 the type colony. Thirty-seven specimens of this lot opened measure: 



(Shells with the ribs weak on penultimate whorl.) 

 One lamella: axial — 

 Length 13, diam. 3.9 mm. 



Two lamellae : axial and superior- 

 Length 12.1, diam. 3.4 mm. 

 11, " 3.4 " 



" 10, " 3.4 " 



