ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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siphon, and does not move its head in the way which is so characteristic 
of the aerial respiration of Ampullaria. The animal comes to the surface, 
extends its siphon into the air, and so renews the air in the lung. 
Lanistes seems to be much less aerial in its respiration than Ampullaria , 
for it comes much less rarely to the surface. The elongation of the 
siphon in Ampullaria and the physiological differentiation between the 
siphon and pallial cleft is to be explained as due to its better adaptation 
to aerial life. The mode of aquatic respiration in Lanistes is very 
similar to that of Ampullaria. 
Olfactory Sense of Snails.* — M. R. Dubois has made a number of 
experiments on the sense of smell in Helix pomatia. He concludes 
that (1) the larger tentacles are more sensitive than any other points of 
the integument ; (2) the sensibility of the smaller tentacles to various 
olfactory stimuli, although very general, is much less marked than that 
of the larger ; (3) the olfactory sensitiveness of the rest of the integument 
is only evident for very few stimuli (such as vapour of benzine), and 
even for these stimuli it is much less marked than that of the tentacles ; 
(4) in the large tentacles sensibility is not confined to the extremities, 
though it is more marked there than elsewhere. The author’s experi- 
ments lead him to think that, for the special senses, primary excitation 
is mechanical, as it is with the tactile organs strictly so called. 
New Neomeniae from the Mediterranean.! — M. G. Pruvot has found 
at Banyuls eight species of Neomenise , all of which, with the exception 
of Proneomenia aglaophenise and P. desiderata, are new. Three of the 
species belong to the genus, lately established by Hubrecht, Dondersia ; 
these are called D. banyulensis, D. jlavens , and D. ichthyodes ; the last 
would deserve separate generic rank did a sufficient number of specimens 
afford material for a comparative study. Paramenia is a new genus 
which exhibits a remarkable mixture of the characters of Neomenia and 
Proneomenia ; three species — P. impexa , P. sierra, and P. palifera — are 
placed in it ; the last of these was, unfortunately, represented by a single 
individual, for the form and distribution of its spicules, the absence of 
penial spicules, and the reduction of the radula afford characters which 
indicate the generic distinctness of the species. Further details are 
promised. 
Circulatory Apparatus and Gonads of Neomeniae.!— M. G. Pruvot 
states that the so-called heart of the Neomenise is very variable in its 
constitution, even within the limits of a single species. In some cases it 
appears to be a simple fold of the dorsal wall of the pericardium, while 
in others it is entirely detached in its median part. It never has any 
muscular elements, but is formed of a mass of connective cells which 
are sometimes arranged compactly and sometimes leave between them 
spaces, in which blood-cells accumulate. It is not connected with a 
dorsal vessel — which does not exist — but with a dorsal sinus. The heart 
also varies considerably inform ; in Dondersia jlavens and D. banyulensis 
it is cylindrical ; in Proneomenia aglaophenise and P. desiderata it is 
flattened and slightly bilobed, while in P. sierra it has the form of a 
* Comptes Rendus, cxi (1890) pp. 66-8. 
f Arch. Zool. Exper. et Gen., viii. (1890) pp. xxi.-iv. 
X Comptes Rendus, cxi. (1890) pp. 59-62. 
2 T 
1890. 
