ARMATURE OF HELICOID LANDSHELLS, 



With a New Species of Plectopylis. 

 By G. K. Gude, F.Z.S. 



{Continued from page 301.) 



pLECTOPYLlS dathraluloides (i) (fig. ^^a-d). 



Colonel Beddome has kindly lent me for 



examination a number of shells of Plectopylis, from 



the Anamullay Hills, which appear to be unde- 



Fig. 44. — Plectopylis clathratiiloides. 



scribed, and for which I adopt the name of Plectopylis 

 clathratiiloides, suggested by Colonel Beddome. It is 

 possible, however, that this form already exists in 

 some collections under the name of P. clathratiila ; 

 for, as already mentioned in discussing that species, 

 I believe the specimens referred to under that name 



(^) Plectopylis c!athrat%iloides, n.sp. — Shell depressed coni- 

 cal, moderately umbilicated, pale corneous, translucent, finely 

 and regularly plicated by raised ribs above, finely and 

 closely ribbed and a little shining below ; whorls 5J slowly 

 increasing, slightly convex, suture impressed. Periphery 

 with an acute compressed keel, above which revolve 2 

 raised spiral ridges, the lower provided with a fringe of 

 coarse hairs. Aperture subquadrate; peristome simple, a 

 little thickened. Umbilicus deep and moderately wide. 

 Parietal armature, one strong, vertical, simple plate. Palatal 

 armature in two series ; upper series with one posterior, 

 vertical, conical tooth and one minute anterior denticle ; 

 lower series, with one posterior, vertical tooth and a small 

 anterior denticle; in addition, one elongated horizontal fold 

 below the umbilical angulation and a small told above the 

 peripherial angulation. Major diameter, 6 millimetres ; minor 

 diameter, 5'5 millimetres ; axis, 3'5 millimetres.— Habitat, Ana- 

 mullay Hills, India.— Type in Colonel Beddome's collection. 



May, 1897.-N0. 36, Vol. HI. U^H. 



in Mr. Nevill's Hand List as from Sikkim belong to 

 this new form. Plectopylis clathratiiloides difTers from 

 P. clathratula in being more elevated, in having a 

 narrower umbilicus, and in being less shining and 

 more tumid below, while it differs from P. reiifera 

 in being less elevated and in having a wider 

 umbilicus ; it is, in fact, intermediate between those 

 two species. The parietal armature consists of a 

 simple, strong, vertical plate, which is not notched, 

 and is without supports (see fig. 44^). The palatal 

 armature is in two series, the first (upper) series 

 consisting of a posterior vertical tooth and a 

 minute anterior denticle ; the second (lower) series 

 being composed of a posterior vertical tooth and a 

 small anterior denticle ; below the umbilical angula- 

 tion there is, besides, an elongated horizontal fold, 

 and above the peripherial angulation a small fold (see 

 fig. 44&, which shows the base of the shell with the 

 palatal armature visible through the shell-wall). 

 The specimen figured is one of the Anamullay 

 Hills specimens belonging to Colonel Beddome's 

 collection. Six specimens from Madura, India, 

 also in Colonel Beddome's collection, I refer to 

 this new form ; four of these are immature and 

 exhibit two sets of armatures, as is the case in 

 immature specimens of P. retifera. 



Mr, E. R. Sykes and others have drawn my 

 attention to the fact that the name Austenia, pro- 

 posed by me for a section of Plectopylis {ante p. 300) 

 is preoccupied. Under these circumstances it is 

 necessary to re-name the section, and I therefore 

 propose the name Sykesia, in honour of Mr. Sykes, 

 who was the first to point out this fact. 





