28 LAND AND FRESHWATER 
organ to immaturity ; but this view was not supported by the exa- 
mination of specimens at all seasons of the year, and some which 
had fully-developed ova. The only conclusion I ean arrive at is 
that the presence or absence of an amatorial sac cannot be consi- 
dered as a character of generic importance ; for it would be simply 
dragging classification into absurdity if we would refer infula and 
attegza to two genera, while almost every other point of organization, 
the form and colour of the animals and of the shells are nearly 
perfectly the same.’ 
I can bear out Stoliezka in these remarks ; for when examining 
two species of the genus Durgella, which is closely allied to Sitala, 
and which I deserted in the Linnean Society’s ‘Journal,’ vol. xv. 
1881, p. 291, I pointed out that the Tenasserim form D. levicula 
possesses an amatory organ, while in D. assamica it was absent, yet 
in every other character there was similarity between them ; and I 
subsequently found that a third species (D. christiane from the An- 
damans) was also deficient of this organ, still preserving the main 
characters of the genus Durgella. 
“ C. infula is a common species in the neighbourhood of Calcutta; 
it occurs sparingly in Western Bengal, and northwards up to the 
foot of the hills, and is also found near Poona and Balarampir in 
Southern India. In none of these localities do the specimens attain 
the size of the Burmese attegia ; and when compared with ordinary 
specimens of the latter, the spiral angle is generally found to be 
smaller, the whorls slightly more convex, and the base of the last less 
inflated. However, these characters are all somewhat variable ; and 
I collected specimens of attegia at Moulmain which are almost un- 
distinguishable from the Bengal infula, the only difference being 
that the former are clearly immature, while the latter, of the same 
size, have all the appearance of full-grown shells.” The above com- 
parative description of the two forms (the italics are mine) is clearly 
shown in the figures I give of them, and to this can be added the 
difference in their sculpture. Nevill, in his ‘ Hand-list,’ records 
twenty specimens of infula from Moulmain, ex coll. Stoliczka ; 
these are probably the immature specimens of attegia referred to 
above : he, at the same time, records S. culmen, Blf., as a synonymn 
of infula, while, as I shall show further on, Stoliczka considered 
culmen to be the young of attegia, which, if it is not distinct, is a 
much more reasonable conclusion. 
“The following measurements have been taken from specimens 
of different localities :— 
Calcutta. Ranigunj. Poona. 
Number of whorls .... 63 7 53 
Larger diameter...... 7°0 mm. 7-5 mm. 5°5 mm. 
Snialler 6+ Pa eee CS 5; COre3 Oo re 
Height of shell ...... POLS 3 US aha, 
Spiral angle ........ (ex 74° 78° 
“I have not seen, from any part of Bengal, specimens larger than 
