436 



MEMOIRS OF THE AMERICAN ACADEMY. 



den ' has also sugc 



e> 



ested in Nemerti 



th 



existence of a rudimentary liver as 



diverticula from the alimentary canal. Keferstein questions the existence of ■ 

 openings in the proboscis of Nemertians, as stated by Williams ; 2 but from what 



found 



Balanoglossus, such a structure is by no means an impossible 



completely disconnected from the main cavity of the alimentary 



though the 



e 



pi 



ion given by Williams of the exister 

 he has probably observed the water 



of two independent stomachs is : 

 tering and leaving the proboscis 



noticed by Kowalevsky and myself in the proboscis of Balanog 



siders the proboscis of Nemertians as an organ of locomotion, 



tained by the structure and function of the proboscis of Balanoglossus 

 view is also 



Kolliker 3 con- 

 opinion fully sus- 



The same 



is also taken by Claparede, 4 after studying the ramifications of the alimentary 

 canal of Eurylepta. 



The history of Balanoglossus as given above, while showing great analogy between 

 the development of Echinoderms and Nemertians, by no means proves the identity 



of type of the Echinoderms and Annuloids 



It 



known which could be taken 



undoubtedly the strongest 



prove their identity ; but when we come carefully 



analyze the anatomy of true Echinoderm larvae, and compare it with that of Tornaria 



find that we leave as wide a gulf 



between the structure of the Echino 



derms and 



of the Annuloids 



1 Van Beneden. Bull. Acad. Brux., XXXII. 



* Williams. Keport Brit. Ann., 1852. 



1 Kolliker. Schweiz. Naturforsch. Ges. 1844. 



* Claparede, E. Recherches Anat. sur les An 



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