SCIENCE-GOSSIP. 



333 



Plectopylis. Its exact locality, unfortimately, was 

 not stated. It differs from P. giardi in being 

 smaller, in having a \vider umbilicus, in the 

 whorls being less tumid and, as a consequence, 

 the two sets of barriers are in close proximity to 

 each other, so that less space is left for the body 

 of the animal when extended out of the shell. 

 The horizontal fold at the aperture is longer than 

 that of P. giardi, and instead of being oblique, as 

 in that species, it is parallel with the sutiu-e and 

 is, besides, distinctly united to the apertural 

 ridge. The principal difference, however, lies in 

 the armatiire, the anterior parietal plate in P. 

 congesta being longer than the posterior one. 



fig. 96, Plectopylis congesta. 



whereas the reverse condition obtains in P. giardi. 

 Moreover, the horizontal fold above the anterior 

 vertical plate of that species is absent in the 

 present shell, while in its place occurs a horizontal 

 ridge uniting the bases of the two vertical plates. 

 The third, fourth, and fifth palatal folds are 

 oblique instead of being almost vertical, as in 

 P. giardi, and nearly straight instead of having 

 their upper and lower extremities bent forwards 

 and backwards respectively. The specimen shown 

 in figs. 96a-c is in Mr. Ponsonby's collection. It 

 measures 18-5 : 15 : 10 millimetres, while figs. 9Gd-f 

 (magnified) are taken from my shell, the dimen- 

 sions of which are 16 : 14 : 9 millimetres. 



(2) Pledopylis achaUnavsiY.repercussoides,n.Ya,r. 

 — This differs from the type in being angulated 

 above at the periphery, also below roimd the 

 umbilicus, and in the peristome being white. 

 Armature same as In the type.— Major diameter, 

 25-27 millimetres ; minor diameter, 19-5-22 milli- 

 meters; altitude, 8-5-9-5 millimetres. — Habitat 

 Biirraa. — Type, ir ray collection. 



The two foregoing species are connected by an 

 intermediate form of Pledopylis still undescribed, 

 but shortly to be pviblished by Dr. Fischer, and 

 which, owing to the kindness of Professor Giard, 

 I was enabled to inspect. This interesting shell 

 combines the characters of the parietal barriers of 

 both the above species, having the two divergent 

 vertical plates and the upper horizontal fold of 

 P. giardi, as well as the lower horizontal fold of 

 P. congetta. In its palatal armatui'e it differs 

 somewhat from both. 



Pledopylis achatina var. repercussoides (^). In 

 addition to the new forms described in my pre- 

 vious communications (ante pp. 115-133, et seq.), I 

 possess a specimen which is intermediate between 

 typical P. achatina and P. repercussa, having the 

 contour and the white peristome of the latter, but 

 the armature of the former. Thinking it vmdesirable 

 to base a variety on a solitary shell, it was tem- 

 porarily placed on one side. Since then Mr. W. E. 

 Collinge has kindly sent me some shells of Pledo- 

 pylis for examination belonging to the museum of 

 Mason's College, Birmingham. Among these I 

 found tlu'ee specimens which are identical with 

 my shell ; all doubts as to its merits to rank as a 

 variety are therefore removed. The variety reper- 

 cussoides differs from the typical P. achatina in 

 being angailated above at the periphery, and 

 below rovmd the lunbilicus, resembling in this 

 respect P. repercussa, with which it has also the 

 white peristome in common. The armature is 

 identical with that of the type. In colour the 

 shell is chestniit brown above, while the vimbilical 

 region is white, a feature it shares with the 

 variety infrafasciata. 



(To he continued.) 



