76 



SCIENCE-GOSSIP. 



sixth folds is a horizontally elongated denticle. (See 

 fig. I02tf, which shows the inside of the outer wall 

 with the palatal folds, and fig. I02c, which gives the 

 anterior view of both armatures). Plectopylis fraiiroisi 

 is intermediate as regards its armature lietween /'. 

 giardi and P. congesta, as already briefly stated when 

 describing the latter species (Science-Gossip N.S. 

 ^"•' P- 333) ■ P- f>'ani;oisi differs from P. giardi, 1° in 

 the anterior parietal plate being more oblique, and 

 2° in this plate being rounded at the upper extremity 

 instead of truncated ; 3° in having an addi- 

 tional free horizontal parietal fold ; 4° in the second 

 and sixth palatal folds being longer; 5° in the second, 

 third, fourth, and fifth palatal folds being more oblique, 

 and 6° in having in addition a denticle between the 

 fifth and sixth folds ; 7' in the armature being further 

 from the aperture, S° in the aperture being less oblique. 



Fig. 102. — Plectopylis frani:oisi. 



•and 9° in the peristome being considerably less 

 thickened and reflexed. The shell is, moreover, 

 considerably smaller, and the sculpture much stronger. 

 From P. congesta it differs similarly in the charac- 

 ters enumerated under Nos. 3, 4, 6, 8, and 9 ; while 

 in the character of the anterior parietal plate it is 

 still further removed, this structure in P. congesta is 

 almost vertical, and it wants the upper free horizontal 

 parietal fold, while the lower horizontal fold is 

 joined to the two transverse plates. The unique 

 specimen is in the collection of Professor Giard, 

 who obligingly sent it to me for examination ; it is, 

 unfortunately, slightly damaged, that portion of the 

 parietal callus which bears the short fold near the 

 aperture in the other species, together with the ridge. 



being broken off, so that it is impossible to say 

 whether the present species differs from its two 

 congeners in this respect. The shell measures major 

 diameter 15.5 millimetres, minor diameter 13.5 milli- 

 metres, altitude 8.75 millimetres. Figs, \02a-b are 

 taken from photographs kindly furnished by Dr. H. 

 Fischer. 



Plectopylis revoluta was described by Dr. Pfeiffer 

 in the " Malakozoologische Blatter," xiv. (1867), 

 p. 64, as from the Andaman Islands. Unfortunately, 

 I have been unsuccessful in tracing the whereabouts 

 of the specimens from which the diagnosis was drawn 

 up, as Mr. Smith, who kindly searched the collection 

 in the British Museum, has been unable to find them 

 there ; and Professor Boettger informs me that they 

 are not in the Pfeiffer collection acquired by 

 Dr. Dohrn. This is all the more to be regretted as 

 no Plectopylis has since been discovered in the 

 Andaman Islands. The late Mr. Stoliczka (" Journ. 

 Asiat. Soc. Bengal," xl. (1871), p. 223) wjis of 

 opinion that this shell could hardly be distinct irom 

 Plectopylis cyclaspis, his specimens of which agreed 

 perfectly with the measurements given by Dr. Pfeift'er. 

 He adds that amongst many thousands of shells from 

 the Andaman Islands, he never received cyclaspis, and 

 he doubted its occurrence there as much as that of 

 /'.(7(7?(Z//;?rt, recorded by Tryon in " Proc. Asiat. Soc," 

 1870, p. 88. It is advisable, I think, to consider 

 P. revoluta synonymous with P. cyclaspis. 

 Addenda. 

 I'lectopylis giardi (fig. 103). — I append a figure 

 showing the inside of the outer wall of F. giardi, with 



Fig-. lo^.^Phclopy lis giaidi (VaXataX folds). 



its palatal folds. This figure, by an oversight, was 

 omitted when the species was described and figured 

 (SciENCE-Gossir, N.S. v., p. 332, fig. 95). 



Plectopylis feddeiii (figs. 104^ and /;).— When con- 

 sidering this species (Science-Gossip, iv., p. 171, 

 fig. 64) I had not seen any specimen, and was obliged 

 to copy Lieut. -Colonel Godwin-Austen's desciiption 

 and figures, in which no indication is given of the 

 palatal armature. :\Ir. W. T. Blanford has oblig- 



Fig. lO^.—PlccioJiylis fcddeni. 



ingly allowed me to examine the type specimens 

 which are in his collection, and I am now able to 

 supplement the figures already published with a view 

 of the palatal armature and one of the parietal 

 armature of an immature shell. The shell of which 



