Miscellaneo us. 155 



transparent Annelida, somewhat like Terehellce, for which M. de 

 Quatrefages proposes the generic name of Apneumea. 



The blood of the Annelida is not always red, as was- supposed by 

 Cuvier ; it is frequently colourless, in many cases it is green, so that 

 nothing general can be said on this subject ; it is perfectly liquid 

 and presents no trace of globules, except however in the Glycerce. 



In the second part, M. de Quatrefages examines the organs of re- 

 spiration, which present no less variability than those of circulation, as 

 may be seen by the following resume : — 



1. Respiration general and entirely cutaneous (Lumbriconereis) . 



2. Respiration cutaneous, but confined to certain segments (Chce- 

 topterus). 



3. Respiration cutaneous, but confined to certain points of each 

 segment {Nereid). 



4. Respiratory organ taking the form of a simple caecum or bladder 

 into which the blood flows (Glycerd). 



5. The branchia is characterized more and more by the formation 

 of a canal in communication with larger or smaller lacunae. 



6. These branchiae may be distributed all along the body (Eunice 

 sanguined) . 



7. They may be confined to a certain number of segments placed 

 towards the middle of the body (Arenicola, Hermella). 



8. They may all be placed at the extremity of the body so as to 

 form a double tuft (Serpula). — Bill. Univ. de Geneve, Sept. 1851, 

 p. 73. 



On the Organ of Smell in the Fluviatile and Terrestrial Gasteropo- 

 dous Mollusca. By M. Moquin-Taxdon. 



In the lower animals it is difficult and often impossible to ascertain 

 exactly what are the organs which preside over the senses, either of 

 hearing or smell ; in many cases it is difficult to prove certainly the 

 existence even of these sensations. In this memoir, If. Moquin- 

 Tandon seeks to prove not only that the Gasteropoda enjoy the sense 

 of smell, but also that the seat of this sense is at the extremity of the 

 tentacles. 



As to the first of these points, the result of various experiments 

 appears to be in the affirmative : thus we frequently see snails and 

 slugs proceed in a direct line towards substances of which they are 

 fond, although they do not ste them ; if the object is removed, or 

 put in a different place, the animal will stop, or change its direction. 

 If there appesirs to be no doubt upon this point, it is by no means the 

 case with the second, as M. Moquin shows by passing in review the 

 various hypotheses which have been proposed on this subject ; he 

 himself thinks that the sense of smell resides in the extremities of the 

 superior tentacles in the quadritentaculate Gasteropoda. In fact, if 

 we dissect a tentacle, we find in it a nervous trunk which terminates 

 in a small dilatation in the terminal knob, after having given rise, at 

 two-thirds of its length from the base, to a delicate filament, which is 

 \hc optic nerve. What appears to prove that it is this nervous fila- 



