HOLOSPIRA. 87 



Mexico : Puebla, State of Puebla, abundant around sulphur 

 springs (Mex. Geogr. Comm.) ; types no. 56932, U. S. N. M. 

 Arizona or New Mexico (Dr. E. Palmer). 



Holospira (Metastoma) pilsbryi BALL., Proc. U. S. Nat. 

 Mus., xviii, p. 4 (1895); xix, p. 349 (1897). 1H. pilocerei 

 var. B, CROSSE & FISCHER, Miss. Scient. Mex., Moll., i, p. 329, 

 pi. 17, f. 5. CROSSE, Journ. de Conch., xl, 1892, p. 266, pi. 5, 

 f. 4, 4 a. 



The whorls are less narrow and crowded than in H. tryoni. 

 The internal pillar (pi. 23, fig. 76) is small, about 0.3 mm. 

 diameter, and of about equal calibre throughout the cylindric 

 portion of the shell. Within the latter part of penultimate 

 and first part of the last whorl it has a distinct spiral swell- 

 ing and twist in the middle ; the pillar in the next earlier two 

 whorls is either without perceptible twist, or visibly swollen 

 near the base; but in still earlier whorls there is a narrow 

 and distinct, though low, spiral ridge, as shown in the figure, 

 which was drawn from one of the type lot, from near the City 

 of Puebla, received from Prof. Ball. It is thus referable to 

 the section Bostrichocentrum, though hardly typically devel- 

 oped for that group. 



According to Ball, "a single specimen was found among 

 loose shells brought home by Br. Palmer after a trip through 

 Arizona and New Mexico, but no particular locality could be 

 assigned to it" (Doll}. Numerous specimens in the collec- 

 tion of the Academy show but little variation. 



Section Haplostemma Ball, 1895. 



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

 Mus., xviii, p. 2; xix, p. 346. 



"Axis moderate, with a short, stout, axial lamella extend- 

 ing about half a gyration in the penultimate whorl, but 

 elsewhere simple and smooth. Type H. mearnsii Ball." 

 (haploos, simple; stemma, wreath.) 



This group is very close to Bostrichocentrum, probably not 

 really separable. 



12. H. MEARNSII Ball. PI. 16, figs. 12, 13. 



Shell small, compact, with 14 whorls, of which 2 are nu- 



