HELIX-LABYRI^THUS. 



pressed; whorls 4J on the specimen before me (5 according to 

 Higgins), gradually widening, scarcely convex, the last depressed, 

 acutely keeled, very deeply, suddenly deflexed anteriorly, constricted 

 behind the peristome and with two short furrows marking the posi- 

 tions of the basal lip-teeth ; aperture very oblique, ear-shaped ; per- 

 istome continuous, white, broadly expanded, subreflexed, outer 

 portion with a short, entering, compressed tooth, basal margin with 

 two small blunt teeth, the outer of which is smaller and marked be- 

 hind the lip by a short groove ; parietal wall traversed by a sinuous 

 elevated callous, giving rise in the middle to an entering, elevated, 

 arcuate lamella; breadth of umbilicus about 3 mill. 

 Alt. 11, diam. niaj. 23 }, min. 20 mill. (Specimen.) 

 Alt. 13, diam. maj. 28, min. 25 mill. (Higgins.) 



Macas, Ecuador. 



Labyrinthus manueli HIGGINS, Proc. Zool. Soc. Lond. 1872, p. 

 686, t. 56, f. 5, 5a. Helix manoeli PFEIFFER, Monographia Hel. 

 Viv., vii, p. 462. " H. manseli" PFR.-CLESS. in Noment. Hel. Viv., 

 p. 175. (?) H. quadridentata HIDALGO, Viage al Pacifico, MoL, p. 

 16, t. 1, f. 8, 9. 



This species resembles H. triplicata in the long parietal lamella ; 

 it differs in being acutely keeled and having a sinuous, not straight, 

 parietal peritreme-edge. From H. leucodon, a very closely related 

 form, it differs in the more sinuous parietal lip, longer parietal 

 lamellar tooth, and more convex base ; If. quadridentata has also a 

 shorter parietal tooth and less sinuous parietal lip than manueli. My 

 description and figures 15, 16 on plate 55, are drawn from a 

 specimen before me which differs somewhat from Higgins's description 

 and figures. The latter were drawn by Sowerby, are evidently 

 inexact and so indistinct that my lithographer has in copying them 

 on pi. 42, figs. 27, 28, misinterpreted the forms of the parietal tooth 

 and that on the outer lip opposite to it. The H. quadridentata of 

 Hidalgo (pi. 41, figs. 20, 21) seems to be this species. 



H. LEUCODON Pfeiffer. PI. 41, figs. 9-11, 14-16. 



Umbilicate depressed, acutely keeled, thin but rather strong, deep 

 blackish-chestnut-colored ; surface shining, lightly obliquely striate, 

 covered with minute sharp granules all over ; spire low, apex obtuse, 

 apical whorl often a little prominent ; sutures a trifle impressed ; 

 whorls 5, nearly flat, slowly, gradually widening, the last acutely 

 keeled at periphery, deeply, angularly constricted back of the peri- 



