504 REPORT ON ZOOLOGY, MDCCCXLIV. 



Annelids is simplified to an extraordinary degree. In the 

 Tubicolse the blood circulates partly in vessels, partly in 

 lacunae ; in Doyeria, Quatref. (allied to Syllls) there is only 

 a simple dorsal vessel, and in Aphlebine, Quatref. (allied to 

 Terebella) neither branchiae nor blood-vessels exist. With 

 respect to the sexual organs, Quatrefages (Comptes rendus, 

 1844, p. 193 ; or Froriep's n. Not. Nr. 674, p. 215) observed 

 distinct sexes in many Dorsibranchiata and Capitibranchiata. 

 He (ib. 1844, p. 77 ; or Ann. d. Sc. Nat. t. i, 1844, p. 22) 

 discovered on the coast of Brittany a Syllis, which, like the 

 Nereis prolifera, Mull., was multiplied by spontaneous 

 fission, after the development of a head upon the anterior 

 extremity of the portion of the body behind a posterior 

 constriction. After the separation the two new individuals 

 are exactly alike, but possess different properties. The an- 

 terior individual probably reproduces its caudal extremity, 

 whilst the posterior propagates itself by means of sexual 

 organs which are developed in it. The small species of 

 Syllis, Nereis, and Poh/noc, which Quatrefages noticed to be 

 luminous, are not, according to his researches (Annales d. 

 Sc. Nat. t. xix, 1813, p. 184; or Froriep's u. Not. Nr. 586, 

 1843, p. 209), provided with any special luminous organs, as 

 the muscles alone develop the light during their contractions. 

 Other researches have convinced him (Comptes rendus, t. 

 xvii, 1843, p. 962; or Institut. 1843, p. 274) that fresh 

 water acts like a poison upon the marine Annelids, which is 

 chiefly owing to the want of chloride of sodium. 



We are indebted to Oersted for a series of systematic 

 essays on the branchiate Annelids. He proposes, instead of 

 the older classification of them according to Audouin and 

 Milne Edwards, and consequently instead of the divisions 

 into Dorsibranchiata, Capitibranchiata and Abranchiata, the 

 following new classification. (Archiv, 1844, Bd. i, p. 99.) 

 He divides them, according to their habitation, into Maricolse, 

 Tubicolse, and Tcrricolre. But this arrangement cannot 

 suffice, since among the Maricolae there are also the bran- 

 chiate Annelids which inhabit tubes, and moreover because 

 many Tcrricoloe live in water. In the classification of the 



