Miscellaneous. 227 



digestion is confounded, so to speak, with those of respiration and 

 circulation. It is this that constitutes the dominant character of 

 the group. 



2. This kind of fusion occasions the disappearance of the organs 

 of respiration properly so called. No Phlebenterate has branchiae 

 in the ordinary sense of the word. 



3. Through the same cause the apparatus of circulation is pro- 

 gressively simplified until its complete annihilation. No Phleben- 

 terate possesses veins ; the arteries and the heart itself disappear in 

 the greater number. When they exist, they are nothing more than 

 organs fitted to agitate and mix the blood. They have no other 

 functions than the dorsal vessel of insects. 



4. In the Enterobranchiata the division of the digestive appa- 

 ratus brings with it the subdivision of the liver. In the Dermo- 

 branchiata this gland only forms a portion of the partitions of the 

 gastro-vascular abdominal pouches. In no Phlebenterate does the 

 liver exist as a distinct organ. In the grouping of the Mollusca this 

 anatomical character belongs as yet exclusively to the group of 

 which we are speaking. 



5. The reproductive apparatus is always asymmetric in the 

 Phlebenterata. Nearly with this exception, the organs both internal 

 and external exhibit a binary lateral symmetry which would be com- 

 plete, did not the anus sometimes swerve to the right of the medial 

 line. Such of these mollusks as possess multiple exterior organs 

 tend, moreover, to repeat them in a longitudinal series. By these 

 two tendencies the Phlebenterata approach the type of the annulated 

 animals. — Comptes Rendus, July 15th, 1844. 



Of the Sexes in Holothuria, Asterias, and Planaria : — Nervous 

 System o/Planariae. 



In a second note, M. de Quatrefages states that by the aid of the 

 microscope he has determined with the most positive certainty, that 

 in Holothuria tubulosa and Asterias rubra the sexes are separate. 

 In each, the testicles are quite like ovaries in form and position ; the 

 nature of the products alone can enable them to be distinguished. 

 He has made similar observations on the Actinia viridis. With re- 

 gard to this latter species, he points out that he could not confound 

 the spermatozoids with the urtical organs that clothe the ovary, and 

 which, taken for the fecundating element by some naturalists, caused 

 them to regard the Actinia as hermaphrodite; for in the Actinia 

 viridis the urtical organs have no resemblance whatever to spermato- 

 zoids, and are from ten to twelve times of greater diameter. 



In the Planar ice, on the other hand, the sexes are really and 

 perfectly united, as Baer and Duges have admitted ; but neither of 

 them had seen the spermatozoids of these animals. M. de Quatrefages 

 states that he has found them in several individuals which likewise 

 bore eggs. The two before-mentioned naturalists had not found any 

 nervous system in the Planarice, and Duges seems even much dis- 

 posed to regard them as possessing none. M. de Quatrefages has 

 detected the existence of this system in several species; it was 



