SCIENCE-GOSSIP. 



231 



ARMATURE OF HELICOID LANDSHELLS 



With New Species op Plectopylis. 



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



{Continued from page 171.J 



pLECTOPYLIS secura (figs. 6yi-d), from Si-lin, locality, received by the writer, from Mr. Hugh 



Fulton, under the name of Plectopylis leiopkis, proved 



in the Chinese province Kouang-Si, was 

 described by Mr. Heude in the "Journal de 

 Conchyliologie," xxxvii. (iSSc)), p. 226, and figured 

 in the third part of his " Notes sur les Mollusques 

 terrestres de la Yallee du Fleuve bleu " (1S90), 

 f. 6. Not having been able to obtain a 

 specimen of this shell, I have been obliged to rely 

 upon Mr. Heude's description and to copy his 

 figures. The shell is described as dextral, discoid, 

 greenish horn-coloured, striated above, shining 

 below, and widely umbilicated, with the spire 

 flattened and the apex scarcely raised. There are 

 six rounded whorls, which increase regularly, the 

 last scarcely descending in front ; the aperture is 

 semi-lunate and strongly oblique; the peristome 

 narrow and reflexed ; the margins are united by 

 a raised flexuous ridge on the parietal wall, and 

 there is an entering horizontal fold. The parietal 

 armature consists of a single vertical plate, which 

 appears to be a little deflected anteriorly below 

 (see fig. 6jd). The palatal armature, as figured, 

 appears to consist of six oblique folds, although 

 the author only mentions four in his diagnosis ; the 

 first fold is minute, situate near the upper suture, 

 the next four stout and oblique, and the sixth 

 thinner and apparently horizontal (see fig 051/). 

 The measurements given are — major diameter, 



1 (after Heude). 



9 millimetres; minor diameter, 7 millir 

 '.-. 4 millimetre*. 



lulu; C) (fig«. 66a-e). I'ivc shells, 

 labelled "Burma," without further indication ol 



• 



•JaaaM* linear raised. 



f, , ... . .. • — : ., 1, ,, mile reunite .1 abovi . 



.1 lltllo 



' s**n* 'an*' 'f ' . :■•'.!•:'■ , ■ ,- j . it ' • ' .ti - ' ' ," 



■M i— tall . ■ ■- ■ ■ ""■■•"•• rl.lic-, 



I lltllo 

 1 1*1 »jll 



upon examination to be distinct, and to belong, in 

 fact, to a different group of Plectopylis. They 

 represent a species — for which I propose the name 



Fig. 66.— Plectopylis leucochilus. 



Plectopylis leucochilus— allied to P. ponsonbyi, but 

 differing from it in the more raised spire and in 

 having a deeper and more perspective umbilicus. 

 In the armature this new species differs from the 

 other members of the group of P. ponsonbyi in 

 having the upper parietal fold uninterrupted. 

 Figs. 6Gn-c show the shell in three different aspects, 

 natural size, while figs. 66d and c are enlarged ; the 

 former shows the parietal wall with its plates and 

 folds, and the latter the inside of the outer wall 

 with the folds and denticles. 



Plectopylis perrierae (-) (figs. 67a-/).— Two speci- 

 mens of an undescribed Plectopylis have been 



with two iran v. rse oblique plates converging upwards, (be 



posterior one ratbi 1 ihin, slightly sinuous, and having a short 



osteriorlj al tbe uppei and lower extremities, the 



11..11. 1, but much stronger and stouter, having 



an ascending ridge posteriorly above and ashorl itout support 



fio 1 rl) Below ; on tbe anterior side are found two • g 

 Ids, tin lowi 1 stout and short and becoming 

 Ht, nuatedi the uppi 1 fold long, rathei thinner, 



following the I thi last whorl .""I terminating 



t> to therli 1 1 tl thi aperture, but nol being united 



a very thin horizontal fold rises below tin transverse plates 



close to the lowei uti n parallel with It, and terminates 



rldgi tl 'i"' .11 ri . Palatal folds, 6< e the Brat neat 



1 mil nearl) horizontal , the second a rtttlo 



,Hqaa and d Si 1 ti d po ti rlorlj the third nearly 



horizontal but more deflected posteriori) , all three bavi .1 



: thi poiti riot • I v foi 



urth ortli il di Bci ted a little 

 md poiti rlorl) bi lo« K ivlng poi ti rlorlj .1 



■mall di iho lowei I and In 1 1 



Mi, n„ fifth It neai tbi lowi 1 ulun . horizontal and 

 M iji ' diameti r, 1 17 miin 



trosi - ide, O : 



millimetre Hat Burma.—'! pi In my coll n 



11. ip. (fig 87a-/) '■ l " " '''■ 



d d «tod pah eo 11 .very 



I, anddecu in 'i bj plrai 1 m 1 



.... n€ d ipi 1 Ittli ral cd, 



■nd regularly, flattened 



dcdocl , H ■ 1 1 ' angul Hi d above [ho periphery 



