182 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Tlie study of the pallial nerves 'shows that the epipodium is inner- 
vated only by the nerves which arise from the two first ganglia of the 
asymmetrical centre, and that all the other pallial nerves which are 
distributed in the median lobe of the mantle also have their origin in 
the two first ganglia of the asymmetrical centre. 
Shell Cavity of Philinidse.* — Prof. P. Pelseneer finds that the 
shell cavity of Philine , or the cavity formed by the mantle which covers 
the shell, is not, as is generally supposed, completely closed ; it commu- 
nicates with the exterior by a canal, the wall of which is formed by a 
ciliated epithelium of some height. The allied Doridium presents much 
the same arrangement. 
The presence of this canal in two Gastropods with a shell cavity 
said to be closed raises the question if Mollusca with an internal shell 
have not also an external orifice to the shell cavity. In a Sepia, and in 
a Pleurobranchus , no canal could be seen. The author suggests that 
various Mollusca with an internal shell have retained a communication 
with the exterior, so that the pressure in the cavity may be the same as 
that outside, whatever changes in depth the animal may undergo. 
Kidney of Snail.f — M. P. Girod finds in the urinary bladder of 
Helix pomatia a special alkaline gland, the function of which is to 
transform, by secretion, into urate of soda the uric acid excreted by the 
kidney. It will be interesting to see if this is true of other Mollusca 
in the excretory cells of which uric deposits have been found. 
New Polycerad.J — Dr- P* Bergh describes from the Adriatic a new 
Dorid which he calls Greilada ( G . elegans sp. n.) ; it stands very near 
to Polycera, but is distinguished by the absolute want of dorsal appen- 
dages. The mandibles are connected with one another by a cuticular 
intermediate piece. In the radula and many parts of the male appa- 
ratus it is almost exactly like Polycera. 
Growth Changes of Radula in Land Mollusca.§ — Dr. Y. Sterki 
finds great variations in the number and shape of the teeth on the radula 
at different stages of life ; it is not yet certain whether new teeth are 
added and changes go on after maturity or not ; in some cases the forms 
of teeth in the embryo are quite different from those of post-embryonic 
life. As the new formation and transformation of teeth is, as a rule, not 
exactly symmetrical on the two sides of a radula, the formula of one side 
is often only approximately true. The increase of width of the whole is 
effected exclusively by the addition of new longitudinal rows. The new 
formation of the radula as a whole is more rapid than is generally 
supposed. 
Mollusca of Water Mains of Paris.]] — M. Locard finds that at least 
forty-four species of Mollusca dwell in the water mains of Paris, and 
four of them are regarded as new. The apparently strange fact of the 
absence of Unio and Anodon is explained by the absence of fish, to which 
the larvae of these common freshwater forms are in the habit of attaching 
* Comptes Rendus, cxvii. (1893) pp. 810 and 11. 
f Op. cit., cxviii. (1894) pp. 294-6. 
J Arch. f. Naturg., lx. (1894) pp. 1-6 (1 pi.). 
§ Proc. Acad. Nat. Sci. Pliilad., 1893, pp. 388-400 (2 pis.), 
il Rev. Scicnt., 1893. See Amer. Natural , xxvii. (1893) p. 1094. 
