98 HOLOSP1RA, SUBG. COELOSTEMMA. 



Fresh-water Shells of N. A., i, p. 24, f. 18; Terr. Moll., iv, 

 p. 150. Holospira roemeri Pfr., TRYON, Amer. Journ. of 

 Conch., iii, p. 312. BINNEY, Terr. Moll., v, p. 177, f . 85 ; Man. 

 Amer. Land Shells, p. 422, f. 467. R. E. C. STEARNS, Proc. 

 U. S. Nat. Mus., xiv, 1891, p. 100. Metastoma roemeri Pfr., 

 STREBEL, Beitrag, iv, p. 80 (1880). 



In this peculiar species the last whorl turns directly for- 

 ward at its termination, becoming in effect sinistral ; there is 

 a strong fold within the right lip, and an excavation in its 

 place on the exterior of the whorl. The columella is notice- 

 ably calloused. It was originally found at New Braunfels, a 

 place evidently at the eastern limit of its range, as the hill 

 country gives place there to a lower and more level region of 

 mesquite chaparral, supporting a different and poorer fauna. 

 Thence it extends to the western extreme of the State near 

 El Paso (figs. 2-5), and northward to the lower lying canons 

 of the Sacramento Mts. in New Mexico (figs. 1, 6, 7). The 

 largest specimens I have seen are from near El Paso. Stearns 

 states that those from Val Verde Co. have 13 to 16 whorls. 

 Shells from the Sacramento Mts. are mainly shorter and 

 broad, though long specimens also occur. Many of the short 

 shells are umbilicate, but others are imperforate. New 

 Braunfels specimens also vary in size. The lower edges of 

 the whorls of the cone sometimes project angularly, as in 

 some individuals of many other species. This is probably 

 due to progressively more unfavorable conditions of nutrition 

 during the period of rapid growth. 



Subgenus COELOSTEMMA Ball, 1895. 



BALL, Nautilus, ix, p. 50 (September, 1895) ; Proc. U. S. 

 Nat. Mus., xix, p. 347. 



Shell many-whorled (17-21 whorls in known species), with 

 short terminal cone, the internal column vertically ribbed (as 

 in Ccclocentrum), and of moderate or large diameter. Type 

 //. elizabethce Pils. (koilos, hollow; slcmma, wreath). 



The known species are Mexican. The group is remarkable 

 for its homoplastic relation to Ccclocentrum, some species 

 having the inlrrnnl pillar gnmulose from interruption or 



