PUNCTUM. 



411 



Jaw of P. pygmcEinn (Morse). 



But one species of this genus has been described, P. pggmceum, Dr., hitherto 

 known in America as Helix minutissima, Lea. A full account of its history, 

 with all published information relat- 

 ing to it, has been given by Mr. Bland 

 and myself in Ann. of Lye. Nat. His. 

 of N. Y., X. 306. The jaw is low, 

 wide, slightly arcuate, with blunt, 

 squarely truncated ends ; it is com- 

 posed of sixteen separate pieces, each 



higher than wide, with slightly overlapping edges ; these pieces do not run 

 obliquely towards the middle of the jaw; there is, therefore, no appearance 

 of an upper median triangular piece, as in Orthalicus and Liguus. 



The lingual membrane is long and narrow. There are 54 rows of 13 — 1 — 13 



teeth each. The centrals have a base of at- 

 tachment much longer than wide, expanded 

 below and squarely truncated, very much 

 narrowed above, reflected. The reflection 

 is very small, and has, according to Morse, 

 one single cusp, but Schacko (Malak. Bl'att., 

 1872, 178) describes the reflection in some 

 European specimens as tricuspid. Laterals 

 of same form as centrals, but with wider base 

 of attachment in the first ones and biscuspid ; outer laterals much narrower. 

 There are no distinct marginals. All the teeth are decidedly separated. 



I have not examined the jaw or lingual membrane of this species, but am 

 entirely dependent on Morse for the descriptions and figures of the American 

 form given above. While treating of the identity of the American and Euro- 

 pean forms in the paper referred to above, we have pointed out the differences 

 in the jaw and membrane of the two forms, which, however, do not appear to 

 be of specific value. 



Punctum pygmaeum, Drap. 



Shell umbilicated, subglobose, reddish horn-color, shining, marked with 

 strong transverse striae and microscopic revolving lines, both most prominent 

 near the umbilicus ; whorls 4, convex, gradually increasing, the last broadly 

 umbilicated ; aperture subcircular, oblique ; peristome simple, acute, its colu- 

 mellar extremity subreflected. Greater diameter, \\ mill; height, 1 mill. 



Helix pygmcca, Drap., etc. 



Helix minutissima, Lea, Trans. Am. Phil. Soc, IX. 17 ; Proe., II. 82 (1841) ; 

 Obs., IV. 17 (1844); Troschel, Arch. f. Nat., 1843, II. 124. — Pfeiffer, 

 Mon. Hel. Viv., I. 87. — W. G. Binney, Terr. Moll., IV. 100, PI. LXXVII. 

 Figs. 6, 7. — Morse, Am. Nat., I. 546, Fig. 45 (1867). 



Helix minuscula, teste Binney, Terr. Moll., II. 221. 



Lingual dentition of P. pygmtrum 

 (Morse). 



