PLECTOPYLIS. 109 



Major diam. 21-24, minor 17-21-5 mm. ; alt. 6-7 mm. 



Hob. Lower Burma : Mule-it range, east of Moulmain 

 (Limborg). 



The shell forming the subject of the present illustration is in 

 Mr. Ponsonby's collection and, being old and weatherworn, does 

 not possess the marginal fringe of hairs referred to and shown in 

 Godwin- Austen's figure. 



The parietal callus has a strong, raised, flexuous ridge, separated 

 from the peristome by a notch above and below, and has, in 

 addition, about the middle, a free lamella, 3 millim. long (see 

 fig. 51 a). The parietal armature further consists of a broad, 

 vertical plate, angulated above, and giving off at its lower end, 



a be 



Fig. 51. Plectopylis brachydiscus. 



towards the aperture, a horizontal plate, 4 millimetres long, which 

 slopes abruptly towards the parietal wall and gradually loses itself, 

 while on the posterior side there is a very short ridge abruptly sloping 

 obliquely downwards (see figs. 51 a and 6) ; about the middle of 

 the vertical plate a free horizontal plate occurs, about 7 millimetres 

 long, separated from the vertical plate by a distance of 1 milli- 

 metre, decreasing in height as it approaches the aperture, and then 

 suddenly terminating (see fig. 51 ). The palatal armature is very 

 curious (see fig. 51 c, which shows it in situ), and consists of six 

 folds ; the first straight and horizontal ; the second also straight 

 and horizontal, but with a small bifurcation at the posterior end ; 

 the third partly horizontal and deflecting posteriorly at an obtuse 

 angle ; the fourth very short horizontally, descending vertically 

 for a short distance and then deflecting posteriorly ; the fifth very 

 short, flexuous, and nearly vertical ; while, finally, the sixth is 

 again almost horizontal. A little below, and to the left of the sixth 

 fold is a small tooth, w r hile above, posteriorly to the first fold, and 

 almost in a line with the bifurcation of the second fold, are three 

 minute teeth. 



In looking through the British Museum collection I came 

 across two immature specimens, which are of interest from the 

 fact that the armature differs in some important particulars from 

 the mature type. The parietal vertical plate in these specimens 

 is sinuous in outline at the upper part, and at its lower extremity 

 gives off anteriorly a horizontal fold 3 mm. long, which slopes 

 abruptly and slightly ascends the parietal wall towards the upper 

 suture ; on the posterior side it is furnished with a short ridge ; a 

 very short horizontal fold occurs between this vertical plate and 



