BULIMULUS-ORTHOTOMIUM. 125 



Bulimus chemnitzioides FBS., P. Z. S., 1850, p. 55, pi. ix, fig. 6.- 

 PFR., MOD. Hel. Viv., iii, p. 303, 1853; Chemn., Conch. Cab., ed. 

 ii, Bulimus no. 113, pi. 31, figs. 21-23. Bulimus (Ncesiotus) chem- 

 nitzioides PFR., Malak. Blatt., p. 160, 1855. Bulimulus (Omphalo- 

 styla) chemnitzioides H. & A. ADS., Gen. Kec. Moll., ii, p. 161, 1855. 

 Bulimulus (Pleuropyrgus) chemnitzioides MARTENS in Albers 

 Heliceeu, ed. ii, p. 221, I860. PFR., Norn. Hel. Viv., p. 254. 1881. 

 -REIBISCH, Isis, 1892, p. 24, t. ii, fig. 4. STEARNS, Proc. U. S. 

 Nat. Mus., xvi, p. 381, 1893. Bulimulus (Pleuropyrgus) lima REI- 

 BISCH, Isis, 1892, p. 25, t. ii, fig. 5. Bulimulus (Ncesiotus) chemnitzi- 

 oides Fbs., DALL, Proc. A. N. S. Phila., 1896, p. 445, pi. 17, f. 4 

 (dentition). 



" The younger specimens named lima by Reibisch (pi. 24, fig. 43) 

 though apparently differing somewhat in form, appear to grade 

 directly into the others. This species sometimes shows a small but 

 distinct parietal tooth or callosity, but this is quite exceptional." 

 (Dall). 



Buliminus lyelliae Beck, Index Moll., p. 70, from the " I. Gallap- 

 pagos," is a nude name. Beck places it between B. calvus and B. 

 Jacob i. 



Subgenus ORTHOTOMIUM Crosse & Fischer, 1874. 



Orthotomium C. & F., Moll. Terr, et Fluv. Mex., i, p. 473, 1874, 

 type B. sufflatus. PILSBRY, Nautilus, ix, p. 114, 1896. DALL, 

 Proc. U. S. Nat. Mus., xix, p. 357, 1897. 



+ Globulinus C. & F., I.e., p. 475, type B.sufflatus; Mormus 

 BINNEY & TRYON, not Albers ; Peronceus, Scutalus, Thaumastus, 

 Mesembrinus of authors, not Albers. 



Shell umbilicate or rimate, varying from ovate-globose to cylin- 

 drical or pillar-shaped; never with spiral color-markings ; with the 

 initial H to 2 whorls sculptured with vertical riblets, the interspaces 

 often minutely striate spirally ; a decided apical dimple or pit. 



Distribution : Central and northern Mexico, southwestern U. S. 

 and Lower California. 



Distinguished from Ncesiotus and Protoglyptus by geographic dis- 

 tribution and the general aspect of the shell, rather than by any 

 definable differences. In other words, while the group is a natural 

 one, comprising specific forms of undoubtedly common ancestry, it 



