Zoological Notices. 169 



ny, under the name of Pyrosoma. Having preserved it in 

 sea-water, I could examine it in a living state. I had pre- 

 viously studied some of these Tunicata preserved in alco- 

 hol at Paris, but then, they have not that crystalline trans- 

 parency which they present during life, and I could acquire 

 but an imperfect idea of their organization. Nothing can be 

 more curious than to obsc^rve the respiratory apparatus of 

 these small animals, when the vibratile ciliae with which each 

 of the branchial openings is furnished, move all at once and 

 turn about with extreme rapidity and perfect harmony. 



But what proved most interesting to me, was the manner 

 in which the circulation of the blood is effected among the Py- 

 rosomas. The heart, which I believe has hitherto escaped the 

 researches of anatomists, is placed in the lower part of the 

 body at the side, and below the mass of the viscera ; its dis- 

 position is analogous to that of the Ascidias. It contracts 

 likewise in a peristaltic manner, and here the direction of this 

 vermicular movement still changes periodically. The direc- 

 tion of the circulating current itself also changes periodically, 

 quite in the same manner as among the Ascidias, and, as in 

 these, the same vessels execute alternately the function of ar- 

 teries and veins. 



Such, then, is the anomalous mode of circulation established 

 in all the great natural divisions of the Tunicata of Lamarck. 

 It has been interesting to me to perceive, that a physiological 

 phenomenon of so remarkable a kind, and which has not hither- 

 to been observed in any other type of the animal kingdom, is 

 not wanting in any of the animals composing the group inter- 

 mediate between the time mollusca and the polypes. — Milne 

 Edwards. 



3. Girculation and Nervous System in the Salpa. — Since 

 I made researches on the circulation of the Pyrosoma, I 

 have had occasion to study the same function among the 

 (Salpa., and I am certain that the description which authors 

 have given of it is far from being correct. 1 have likewise as- 

 certained the existence of a nervous system in these animals, 

 a fact which had escaped M. Savigny, and which, I believe has 

 not been remarked by any other anatomist. — Milne Edicards. 



4. Carinaria, — All the Mollusca of the order Heteropoda 



