PUNCTUM. 413 



minutissima as occurring in Massachusetts, adding in a note " the character of 

 the jaw would place the species in the subfamily Orthalicince, as a distinct 

 genus for which Morse's name Punctum might be retained, otherwise the 

 species would be placed in Hyalina." 



Mr. J. Gwyn Jeffreys (Ann. &. Mag. Nat. Hist., Oct., 1872) refers to 

 Hyalina minutissima as being identical with Helix pygmcea, Drap. 



Dr. G. Schacko (Malak. Blatt,, p. 1 78, 1872) has recently described both jaw 

 and lingual teeth of //. pygmcea, showing that both have the same characters 

 as ascribed by Morse to Punctum minulissimum. 



The following is a translation of Schacko's description of the jaw of //. 

 pygmcea : - 



The jaw consists of nineteen plates, which are grouped in the form of a horse- 

 shoe. They lie together like the tiles of a roof, and partially cover one another. 

 The plates are connected by a fine transparent membrane. The middle plate, which 

 is the largest, and perfectly straight at the top, lies entirely alone, so that a space is 

 visible between it and the two next side-plates. These are smaller and of the same 

 length, while the top is slightly curved. The plates have the same form as regards 

 their length, but the curve increases towards the end plates. The third plate from 

 the middle begins to cover the second, the fifth covers half of the fourth, and the 

 succeeding plates always more, until the last covers two thirds of the preceding 

 one. 



The formula of the lingual membrane is given by Schacko as being 114 rows 

 of 19 1 19 ; by Morse of Lea's species, 51 rows of 13 1 13. 



The centrals of //. pygmcea are said by Schacko to be tricuspid ; the two 

 side cusps so small, and scarcely recognizable, that they entirely disappeared 

 in one specimen ; the laterals bicuspid. He remarks that every tooth of the 

 radula lies alone, so that even the cutting points do not cover or disturb the 

 basal surfaces of the overlying rows. 



Schacko refers to the near alliance, in form of jaw especially, of H. pygmcea 

 with //. minutissima of the genus Punctum of Morse. 



Looking at the descriptions and figures of the jaws of pygmcea and minutis- 

 sima, we notice, with striking general similarity of characters, some differ- 

 ences ; on the other hand the lingual teeth of the two forms appear to be the 

 same, and the shells without variation of specific value. The description of 

 jaw and lingual dentition of the species is given above. 



The facts regarding the distribution of //. pygmcea, which may be treated as 

 one of the circumpolar species, favor the opinion, which we are disposed to 

 adopt, that Lea's specific name must be placed in the synonymy of Punctum 

 pijgmceum. 



Moquin-Tandon describes the genitaliaof the European form to have neither 

 dart nor multifid vesicles. 



