﻿NO. 14 LANDSHELLS COLLECTED IN PERU IN I9II DALL 7 



simple, without irregularities or laminae on any part of the interior 

 surface. U. S. N. Mus., No. 214369. 



There are a number of species which have been referred to this 

 group which do not agree with Aiaxus except in external characters. 

 They have developed an elaborate system of lamination within the 

 whorl, but so far back from the aperture that only by opening the 

 shell can it be observed, somewhat as in Holospira. 



The species I have been able to examine are scalaricosta Morelet, 

 infundibulum Pfeiffer, umbilicatellus Pilsbry, tubulatus Morelet, and 

 spiculatus Morelet, which last from its want of the wide umbilicus 

 had been referred to Peronmis. 



It is evident that a new name is required for the forms with an 

 internal armature, for which I propose the name Phenacotaxus and 

 divide this into two sections, Phenacotaxus s. s. and Ataxellus; as 

 follows: 



Subgenus PHENACOTAXUS Dall, nov. 

 Type Bulimulus (Ataxus) umbilicatellus Pilsbry. 



Shell elongate or fusiform, slender, axially sculptured, the pillar 

 with a plication beginning in the posterior half of the last whorl and 

 extending nearly to the apex, the plica at intervals widely expanding 

 laterally into the lumen of the whorl. 



Section Phenacotaxus s. s. 

 Shell with a funicular wide umbilicus extending to the apex, nar- 

 rowing the whorl and aperture, and making the axis tubular. 



Section Ataxellus Dall, nov. 

 Shell very elongate, imperforate, the axis thread-like, gyrate. Type 

 (Bulimus spiculatus Morelet, var. ?) A. pectinatus Dall, n. sp.? 



PHENACOTAXUS SCALARICOSTA Morelet 



Bulimus scalaricosta Mor., Journ. de Conchyl., vol. 8, i860, p. 375; Ser. 

 Conchyl. vol. 3, p. 205, pi. 11, f. 8, Apr. 1863. (Plateau of Andamarca, 

 province of Cuzco, Peru.) 



Between Ollantaytambo and Maras, Peru, at 10,000 to 11,000 feet 

 elevation. U. S. N. Mus., No. 250262. 



This species has a narrow holostomate aperture almost separated 

 from the preceding whorl. 



The axial plica is invisible from the aperture and begins in the first 

 half of the last whorl near the base, where it forms a broad, strong 

 lamella curving distally toward the base of the whorl, and about half 



