i8i 



SCIENCE-GOSSIP. 



side are, besides, two minute folds, one horizontal 

 near the upper extremity, the other vertical near 

 the lower extremity, the latter being the larger of 



Fig. 26. — Plectopylis cuiisculpta. 



the two (figs. 26a and b). The palatal armature 

 consists of six folds more or less horizontal, the first 

 short and thin, near the suture, the second a little 

 larger, bilobed ; the third, fourth, and fifth longer, 

 broader, obliquely descending posteriorly, and 

 each giving off a minute denticle ; the sixth very 

 short as seen in fig. 26c. (The first fold has 

 accidently been omitted in this figure.) The 

 specimen is in Mr. Ponsonby's collection. 



Plectopylis multispira (figs, ^ja-d), from the 

 Province of Hou-Nan, was described by Dr. von 

 MoUendorff in the " Nachrichtsblatt der Deutschen 

 Malakazoologischen Gesellschaft," xv. (1883), p. 

 loi, and figured by him in the " Jahrbuch Deutsch. 

 Malak. Gesells. x. (1883), t. 12. f. 10, The shell 

 is thin, subpellucid, yellowish corneous, shining 

 above and below, widely umbilicated, composed of 

 seven closely and regularly coiled whorls, gradually 

 and slowly increasing, finely striated, the last 

 whorl being wider and shortly deflected in 

 front. It measures from 8 to 11 millimetres in 

 diameter. The parietal armature is composed 



Fig. 27.— Plectopylis multispira. 



of a strong lunate plate which descends obliquely 

 posteriorly, the convex side being towards the 

 aperture (fig. 27a) ; on the anterior side are found : 

 first, a short horizontal fold in a line with the 

 upper extremity of the vertical plate ; below this, 

 almost in a line, are five minute denticles, the 

 second auA third of which are united so as to form 



a double one, while the fifth is a little elongated and 

 slants obliquely downwards (see figs. 27* and c). 

 The palatal armature (figs. 27^, b, and d) is composed 

 of six more or less horizontal folds : the first very 

 short and thin, near the suture ; the second, third, 

 fourth, and fifth stronger and broader, equidistant and 

 parallel, obliquely slanting downwards, and slightly 

 indented posteriorly ; the sixth a little narrower, 

 near the lower suture ; between the fifth and sixth 

 folds, a little beyond their posterior extremities, is 

 found a little elongated denticle. Fig. 27^ shows 

 the whole armature from the posterior side, fig. 276 

 from the anterior side, while fig. 27^ shows the 

 inner side of the outer wall with its folds. The 

 specimen figured is in my collection, and measures 

 10 millimetres in diameter. 



Plectopylis invia (figs. 28a and b) was described 

 and figured by the Rev. P. Heude, in Part 2 of his 

 ' ' Notes sur les Mollusques Terrestres de la Vallee du 

 Fleuve Bleu," published in the " Memoires con- 

 cernant I'Histoire Naturelle de I'Empire Chinois " 

 (1885), p. Ill, t. 30, f. 4, from specimens collected 



Fig. 28. — Plectopylis invia. 



in Tchen-Keou. The shell somewhat resembles 

 P. mtiltispira in outline and texture, but it is 

 more strongly ribbed and less transparent ; it is 

 composed of only six whorls and it measures only 

 8 millimetres in diameter; the umbilicus is very 

 deep. The parietal callus forms a raised ridge, not 

 continuous with the margins of the peristome, and 

 giving off a little above the middle a short entering 

 fold. The parietal armature (see fig. 28a) further 

 consists of a slightly curved vertical plate, giving 

 off anteriorly at the upper extremity a very slight 

 horizontal support. The specimen here figured 

 has, in addition, a second smaller vertical fold 

 posteriorly to the principal one, but whether this 

 is a normal condition I am unable to say, having 

 only a single specimen to examine. The principal 

 vertical plate has also posteriorly a slight support 

 at the lower extremity. The palatal armature 

 consists of five folds, the first, facing the upper 

 extremity of the parietal fold, thin and longer than 

 the others, attenuated anteriorly and nearly 

 horizontal; the second, third, and fourth are short 

 and broad, very oblique, almost vertical, and con- 

 nected by a slight attenuated callous ridge, which 

 is continued below the fourth fold ; the fifth is 

 thin, horizontal, and situate near the lower suture 

 (see fig. 28b). The specimen which I have been 

 allowed to open is in Mr. Ponsonby's collection ; 

 it measures 65 millimetres in diameter. 

 (To be continued.) 



