246 THE RELATIONS OF ZOOPHYTA 



which form a series of transitions of a most unmistakable 

 character, finally leading from the one before us to those which 

 have a decidedly articulate body. It is to be noted that the latter 

 as well as the former, and the species before us, have a so-called 

 " nucleus," i. e., a reproductive organ, (ov,) and moreover the 

 peculiar hook-shaped body which is so prominent in some of the 

 jointed forms is also present (m) in the one which I have illus- 

 trated. In conclusion, therefore, it may be said that everything 

 tends to show that the Opalinas are members of the group of 

 Articulata, whilst, on the other hand, their relationship to Pro- 

 tozoa is based upon far-fetched resemblances. 



Zoophyta and Articulata. I have already spoken of the con- 

 tested position of certain worm-like animals, which had beer, 

 classed among the Zoophytes by the earlier naturalists, and as '. 

 gave such a full description of two of these forms, e. g., Can- 

 dina (figs. 114, 115, 116) and Bonellia (figs. 126, 127), which 

 most closely approximate each other, from each side of the di- 

 viding line between Zoophyta and Articulata, I shall only recur 

 to them again simply to mention the most characteristic features 

 which separate the one from the other. In the Caudina, (fig. 

 114,) it is the strict conformation to the Zoophytic type, the sys- 

 tematic lateral repetitions of the organs, such as the aquiferous 

 circulatory tubes, (aq to aq 1 ,} the nervous cords, (fig. 116, w,) and 

 the muscular bands (fig. 115, ms) along the sides of the body, 

 which distinguish it from all Articulata; and, on the other hand, 

 in Bonellia, (fig. 126,) it is not only the single ventral nervous 

 cord (g-, g- 1 , g* 3 ) and its peculiar loop (</ 2 ) about the throat, but 

 also its series of numerous, successively repeated, longitudinally 

 arranged ganglionic enlargements, (f/ 1 ,) and the therefrom arising 

 transverse nervous threads, which give it an unquestionable claim 

 to be ranged in the type of Articulata ; whilst a total absence of 

 anything like a lateral repetition of the organs offers no chance 

 whatever for a comparison in this respect with the Zoophyta ; 

 not even with the singularly worm-like Caudina. 



Bryozoa and Zoophyta, It is contended by eminent author- 

 ity, even at the present day, that the Bryozoans belong to the 



