348 Prof. E. Claparede on the Structure of the Annelida. 



More or less complete muscular floors sometimes divide the 

 perivisceral cavity into several cliambers. M. de Quatrefages 

 cites, as presenting this arrangement, the genus Polijophthahna 

 and Terehella conchilega. Many other examples might be cited. 

 Such are : — the Opheliea, the Polycirrida, many Terebellea, the 

 Aphroditea, and the great majority of the Annelida Errantia, in 

 which the perivisceral cavity is divided into three longitudinal 

 chambers ; the Glycerea, in which it is divided into two, &c. 



Digestive Organs. 



For the diflFerent parts of the alimentary tube and, especially, 

 of the trunk, M. de Quatrefages has endeavoured to estabhsh a 

 complete nomenclature, the opportuneness of which is at least 

 contestable so long as the homologies upon which it is supposed 

 to be founded are by no means demonstrated. Why, for exam- 

 ple, in the Syllideu, should we give the name of dentary region 

 of the trunk to an organ with glandulous walls, which constitutes 

 no part of the trunk and contains no teeth* ? The names em- 

 ployed by other authors — such as fleshy portion of the pharynx 

 (Milne-Edw.), gizzard (Williams), and proventricuius (CErsted) — 

 appear to me to be very preferable. Are there any sufficient 

 reasons for setting aside the names ventriculus and glands of the 

 ventriculus, employed originally by Rathke for the Nereidea, and 

 repeated by his successors ? Is it really necessary to replace 

 them by those of oesophagus and salivary glands f? I do not 

 think so. Rathke's names were at least justified by analogy. 

 One generally regards the salivary glands as more or less con- 

 nected with the buccal cavity, whilst the glands in question 

 often occur twenty or thirty segments behind the buccal seg- 

 ment. 



In certain Annelida the posterior region of the intestine, fol- 

 lowing the biliary region, acquires a peculiar appearance. Its 

 wall becomes filled with cells secreting curious concretions de- 

 stined, no doubt, to be eliminated with the faeces. I designate 

 this part of the intestine by the name of the urinary region, 

 although, chemically, it does not seem to contain any uric acid J. 



* M. (le Quatrefages, it is true, enumer.ates a certain niuuber of Syllidea 

 armed with teeth in this region ; but we shall find that in most eases, ))ro- 

 bably even in all, there is an error, and that the worms in question belong 

 to totally different families. 



t This name of salivary glands is indeed borrowed from Rud. Wagner, 

 who employed it, as well as that of poison-glands, because he assumed that 

 a canal starting from these glands penetrated to the extremity of the jaws. 

 This canal does not exist. (See " Zur Anatomie von Nereis," Isis, 1834, 

 p. 133.) 



X I shall speak of this again in more detail in connexion with certain 

 Syllidea. 



