ANGUILLULJ! 577 



and 59. Dr. Carpenter believes that this creature "is 

 a degraded form of the annelidan type its nearest affi- 

 nities being (as already pointed out by Drs. Leuckart 

 and Pagenstecher) the chaetopod or setigerous Annelids. 

 Every part of the characteristic organization of the type 

 is here reduced to the extreme of simplicity. The alimen- 

 tary canal passes in a straight line from one extremity of 

 the body to the other, without either sacculations or glan- 

 dular appendages. The nutritive fluid which transudes 

 through its walls, and which finds its way into the peri- 

 visceral cavity, is distributed throughout the body solely 

 by means of extensions of that cavity, through which it is 

 propelled in part by the agency of cilia that clothe its walls. 

 This fluid is obviously the homologue of the blood of higher 

 animals, that we cannot but regard the existence of the type 

 of structure before us (the wonderful transparency of the 

 body not permitting the slightest doubt as to the absence 

 of anything resembling a dorsal vessel) as affording a 

 further confirmation of the view of the so-called circulat- 

 ing apparatus of the higher Annelida, which regards their 

 perivisceral cavity and its extensions as representing the 

 proper sanguiferous system, and which looks upon the 

 system of vessels containing coloured fluid as a special 

 arrangement having reference rather to the respiratory 

 functions. 1 The extreme tenuity of the walls of the body 

 and its appendages renders it unnecessary that any special 

 provision should be made for the aeration of the nutritive 

 fluid ; and we accordingly find neither branchiae nor any 

 trace of what is commonly described as the sanguiferous 

 system in Annelida. The centres of the nervous system 

 would seem to consist solely of the cephalic ganglia the 

 absence of the ordinary longitudinal series being apparently 

 related to the very incomplete segmentation of the body, 

 and constituting a link of affinity to the Turbellarian 

 Worms. The ocelli present a condition of extreme sim- 

 plicity, yet the duplication of the corneale in each of them 

 marks that tendency to repetition which so peculiarly 

 distinguishes the Articulate type. It is, however, the 

 extreme simpl'city of its generative apparatus that con- 



(1) See Prof. Huxley's Lectures in Medical Times and Gazette. July 12 and 26, 

 1856. 



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