HUNGARIAN NERITI NÆ. 
459 
of the Hungarian National Museum. — Since, however, the thermal 
spring of the Püspökfürdő is at present in the very same condition as 
it was at that time, living specimens are likely to be found there even 
to day. That none have been found of late shows that they have probably 
been looked for at any places but the ones where as I learn from the 
verbal communications of Mr. A. Mocsáry — they occur i. e. settled on 
the lower surface of pieces of stone and wood sunk to the bottom, — 
so that it is, indeed, anything but an easy task to bring them to light, 
even by dredging. Unfortunately I have not yet had the opportunity 
of collecting there and must be content with conjectures, 
The Neritina collected at Püspökfürdő by Messrs. Hazay and 
Mocsáry differ from the allied forms found at Tata in colouring 
only; they are to be regarded, therefore, as N. Prevostiana, which is 
grayish brown, intersected by bright zig-zag lines, and so marked in 
much the same way as the Tata specimens. The forms most nearly 
allied to N. Prevostiana disclose similar characters in colour and mar¬ 
king. In Algiers there live, according to Martens, along with one another 
two forms of N. numidica, one black throughout, the other reticulately 
marked. The same holds good for N. baetiea, N. meridionalis , N. pelo- 
ponnesia and N. sardoa. 
The strict structural affinities existing between the N. Prevostiana 
of Tata and N. danubialis, have once been mentioned before. The two 
points of difference were mentioned there to be nothing more than the 
smaller and shorter size of the former, and N. danubialis having brown¬ 
ish colour adorned with dark and bright lines, which are, in the majo¬ 
rity of cases, undulating and narrow, instead of broad and zig-zagged. 
On account of their main colour being like that of N. danubialis , 
the Püspökfürdő forms even surpass their Tata relatives in resem¬ 
blance, and the slight deviations existing between the two are still 
lessened when we consider that there are variative forms of N. danu¬ 
bialis which exhibit the same short, thichset shape scarcely differing 
in marking from the N. Prevostiana of Püspökfürdő. Such specimens 
were sent to me from Szászka, dredged from the small river Néra not 
long ago. Apart from their larger size, they agree so closely with the 
Püspökfürdő forms that no one would fail to take them for N. Pre¬ 
vostiana with absolute certainty, were they not connected by interme¬ 
diate forms to N. danubialis. 
The peculiar forms of the Hungarian N. Prevostiana occurring at 
Tata and Püspökfürdő, as well as the specimens of A. danubialis from 
Szászka, have an importance on account of the fact that they point to a 
close relationship that seems to exist between the two species hitherto 
