SCIENCE-GOSSIP. 



333 



Plectopylis. Its exact locality, imfortvinately, was 

 not stated. It differs from P. giardi in being 

 smaller, in having a wider timbiliciis, 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 oiit of the shell. 

 The horizontal fold at the aperture is longer than 

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

 in that species, it is parallel with the suture and 

 is,' besides, distinctly united to the apertural 

 ridge. The principal difference, however, lies in 

 the armature, 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. 96d-f 

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

 sions of which are 16 : 14 : 9 millimetres, 



( ^ ) Plectopylis achatina var. repercussoides, n. var. 

 — This differs from the type in being angulated 

 above at the periphery, also below round the 

 umbilicus, and in the peristome being white. 

 Armatiu-e same as in the type. — Major diameter, 

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

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

 Burma. — Type in my collection. 



The two foregoing species are connected by an 

 intermediate form of Plectopylis still tmdescribed, 

 but shortly to be published 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 armature it differs 

 somewhat from both. 



Plectopylis achatina var. repiercussoides (^). 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 

 contoiu- and the white peristome of the latter, but 

 the armature of the former. Thinking it undesirable 

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

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

 Collinge has kindly sent me some shells of Plecto- 

 pylis for examination belonging to the museum of 

 Mason's College, Bii-mingham. Among these I 

 found three 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 angulated above at the periphery, and 

 below rormd the umbilicris, 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 chestnut brown above, while the umbilical 

 region is white, a feature it shares with the 

 variety irifrafasciata. 



(To be continued.) 



SATURN'S NINTH MOON. 



IT is ann oun ced that Prof .W. Pickering,brother of 

 the director of the Lowell Observatory at Har- 

 vard University, has taken several photographic 

 plates of the planet Saturn, which show a ninth satel- 

 lite, hitherto iinknown to astronomers. The photo- 

 graphs were taken with the Catherine Bruce 

 telescope, at the Arequipa Observatory, in Peru. 

 This " new " luoon is three-and-a-half times more 

 remote from Saturn than lapetus, the outermost 

 known satellite. The nearest moon to that planet is 

 Mimas, distant 117,000 miles, and having a revolu- 

 tion period of 22 hrs. 37 min. and 5'7 sec. lapetus 

 is distant 2,225,000 railes, with a revolution of 

 79 dys. 7 hrs. 54 min. 17"1 sec. The new unnamed 

 moon has a period of revolution of seventeen 

 months. The Americans with their fine instru- 

 ments, and bi'illiant atmosphere, are becoming the 

 leaders in the science of astronomy. 



