SCIENCE-GOSSIP. 



245 



last being a little wider than the preceding, 

 angulated above the periphery and descending 

 anteriorly. The peristome is white, somewhat 

 thin, but reflexed ; the parietal callus has a raised 

 flexuous ridge, separated from the lower margin of 

 the peristome and notched at its junction with the 

 upper margin. The parietal armature consists of 

 a long horizontal fold, united to the ridge at the 

 aperture, and proceeding parallel with the last 

 whorl for a quarter of its length, at Which point it 



Fig- 35- — Plcctopylis kavcnorum. 



gives off a shortly descending arm ; it then 

 rises obliquely for a short distance and finally 

 bifurcates, the lower arm of the bifurcation being 

 the longer, and obliquely descending, while the 

 upper arm is slightly curved backwards ; the 

 single arm f^r^st mentioned has posteriorly at its 

 lower termination a short obliquely descending 

 ridge, and a little higher up anteriorly a stronger 

 obliquely ascending ridge, while the lower arm 

 of the bifurcation has posteriorly at its lower 

 termination a short obliquely descending ridge, 

 (see fig. 35a). Below this complicated plate 

 there is a free, thin horizontal fold close to the 

 lower suture, also united to the ridge at the 

 aperture (see also fig. 355, which shows both 

 armatures from the side of the aperture, and 

 fig- ^5'^. which gives their posterior view). The 

 palatal armature consists of: first, a thin and long 

 horizontal fold parallel with and near the suture ; 

 secondly, another thin but shorter fold which at 

 first proceeds horizontally, then suddenly deflects 

 posteriorly with a slight curve backwards, a small 

 denticle occurring posteriorly in a line with the 

 main horizontal portion ; thirdly, a short, some- 

 what stouter, crescent-shaped fold, with its concave 

 side facing the aperture and lower suture ; fourthly, 

 a strong vertical fold, with two minute denticles 

 posteriorly near its lower end ; and fifthly, a thin 

 horizontal fold, slightly reflexed in the middle 

 (see fig. 35(f, which shows the inside of the outer 

 wall). The specimen figured is in the collection 

 of jNIr. Ponsonby ; it measures 135 millimetres 

 in diameter. 



In looking over the specimens of Plcctopylis of 



the McAndrew collection in the University Museum 

 of Zoology, Cambridge, I found three specimens 

 labelled Pkctopylis burniani, Benson, doubtless a 

 misspelling for P. bnymanica, one of Mr. Benson's 

 MS. names. On comparing them with Pkctopylis 

 harenorum, I found them to belong to that species. 

 As I have reason to think that P. harenorum exists 

 in some collections under the name of P. burmanica, 

 and as, moreover, this MS. name was never, to 

 my knowledge, published by Mr. Benson, I have 

 thought it useful to make mention of the above 

 fact. 



Plcctopylis laomontana (figs. 36a-c), from Laos, 

 was described by Dr. Pfeiffer in the " Proceedings 

 of the Zoological Society," 1862, p. 272, and 

 figured by him in " Novitates Conchologicae," ii., 

 t. 57, ff, 7-9 (1863). It was also figured in 

 Mouhot's " Travels in the Central parts of Indo- 

 china (Siam), Cambodia, and Laos," ii. (1864), 

 figs. 9 and 10. As the armature has not hitherto 

 been figured, I am pleased to have had the oppor- 

 tunity of doing so. The shell is solid, disk-shaped, 

 with the apex scarcely raised above the flattened 

 spire, chestnut brown, finely ribbed above, 

 smoother below, with scarcely any trace of spiral 

 sculpture. It is composed of six or six and a-half 

 whorls, the last of which widens rather suddenly, 

 descends abruptly and shortly in front, and is 

 slightly constricted behind the peristome, which 

 is whitish, thickened and reflexed, and has its 

 margins united by the raised, slightly curved ridge 

 of the parietal callus, but a little notch occurs at 

 the junctions above and below. The parietal 

 armature consists of a single strong, solid lunate 

 plate, with its concave side facing the aperture, 

 and deflexed posteriorly below. (See fig. 36^, 

 which gives the posterior view of both armatures.) 

 The palatal armature consists of : first, a short 

 horizontal fold near the suture ; secondly, a stouter 



Fig. 36. — Plcctopylis laomcntana. 



and somewhat longer horizontal fold, shortly 

 bifurcated posteriorly, the upper arm proceeding 

 horizontally, and the lower and shorter one 

 descending obliquely ; thirdly, a shorter stout fold 

 which proceeds at first nearly horizontally, then 

 deflects a little about the middle, the anterior half 

 being a little indented ; fourthly, a short, stout, 

 straight fold, descending a little obliquely pos- 

 teriorly, and also a little indented in the anterior 

 half ; fifthlv, another straight, short, stout fold, also 



