138 



HELICID^. 



sinuous raised ridge on the parietal wall at the aperture connects 

 the margins of the peristome ; at the junctions above and below, 

 however, there are slight notches. The armature is similar in 

 most respects to that of P. reperciissa, but it is less solid and 

 heavy; Vae lower Vivm oi the bifurcation on the parietal wall is 

 longer than the upper, and the thin free horizontal fold near the 

 lower suture is not united to the ridge at the aperture and does 

 not proceed beyond the lower arm of the hifurcation as is the case 

 in P. reperciissa. The upper fold of the palatal armature is much 

 shorter than in that species, terminating posteriorly at the same 

 point as the slioi'ter upper arm of the parietal bifurcation ; the 

 second and fiftli horizontal palatal folds are much shorter an- 

 teriorly than in P. repercussa ; while the vertical palatal lamina 

 (the fourth) is broader, but less stout and less inclined towards 

 the aperture than in that species. 



The specimen shown in figs. 69 d and e is from Moulmain and 

 is in my collection. It measures : major diam. 28, minor 22, 

 alt. 7"5 mm. I'ig. 69/ shows the posterior aspect of its parietal 

 and palatal armature. Figs. 69 a-c are reproduced from photo- 

 graphs (natui-al size) of Gould's types in the N'ew York State 

 Museum, Dr. Bagg having supplied the following notes : " Ileliv 

 unguina, Gould. Catalogue number, 251 ; Original number, 

 A 558. The shell is somewhat banded by brownish and white 

 alternating, but not in all specimens." 



116. Plectopylis bensoni, Gude, nom. mut. 



Helix achatina (Grav), Pfeiffer, Zeits. Malak. ii, 1845, p. 86 ; Benson, 

 A. M. N. H. ser. 3, iv, 1859, p. 69 ; Kobelt, 111, Conch. 13uch, 

 ii, 1879, pi. 71, tig. 9. 



Helir (Plectopylis) achatina, ]5enson, A. M. N. II. ser. 3, v, 1860, 



ser. 2, vii, 1889, p. 47. 

 Helix {Atopa (Plectopylis)) achatina, Tryon, Miin. Conch, ser. 2, 



iii, 1887, p. 165, pi. 35, tio-g. 3_5^ 7^ 8. 

 Plectopylis achatina, Stoliczka, J. A. S. B. xl, 1871, p. 221, pi. 15, 



figs. 1-3 (auatomy) ; Pilsbry, Man. Conch, ser. 2, ix, 1894, p. 145 ; 



Gude, Science Gossip, n. s.\-, 1898, p. 114, tigs. 80-82. 

 Plectopylis (s. s.) achatina, Gude, op. cit. vi, 1899, p. 148. 



Original description: — "T. siuistrorsa, latissima umbilicata, 

 depressissima, discoidea, laevigata, superne rufa, albido maculata 

 et flammata, basi pallida; spira plana, medio vix elevatiuscula ; 

 anfr. 6| subplanulati, ultimus a latere subcompressus, antice 

 subito deflexus ; apertura subhorizontalis, oblongo-subcircularis ; 

 perist. fusculum, undique expansnm et reflexum, marginibus 

 lamina prominente, lamellam profunde intrantem emittente 

 junctis. 



" Diam. major. 31, minor 24, alt. S^ mill."' (Pfeifer.) 



