474 NOTES. 



a provisional stage in the hypothetic reconstruction of the 

 unknown, long extinct parent-form of Vertebrates, an "Archi- 

 tjpe." 



86 (i. 258). Only very uncertain assumptions can be made 

 as to the sense-organs of the hypothetic parent-form, for these 

 organs, more than any others, have been subject to adaptations, 

 and in Ascidia, as in the Amphioxus, have probably been much 

 atrophied. The earliest Vertebrates probably inherited a pair 

 of eyes of very simple character and a pair of simple ear- vesicles 

 from Worms. 



87 (i. 267). The primitive kidneys were perhaps already 

 metameric in the hypothetic parent-form of Vertebrates, so that 

 in addition to the two longitudinal main canals (primitive 

 kidney ducts) numerous transverse tubes (segmental canals) 

 were connected with these main canals, a pair in each metameron 

 of the middle part of the body. Perhaps these already opened 

 through ciliated funnels into the body-cavity (^cceloma), as is 

 now the case in Annelids, and, according to Balfour, in the 

 embryos of Selachii. Cf. Balfour, " Development of Elasmo- 

 branch Fishes." " Quarterly Journal of Microscopical Science." 

 New Series, vol. xiv. p. 323 ; " Journal of Anat. and Physiol." 

 vol. x. 



88 (i. 273). The germination of Primitive Vertebrates. Cf. 

 with Table VI., Table VII. (vol. i. p. 327), Table XL (p. 467); 

 also the diagrammatic figures in Plates IV. and V. with explana- 

 tion (p. 321). 



89 (i. 276). The Germ-forms of the earliest Vertebrates, as 

 they are represented in diagrammatic cross sections in Figs. 

 62-69, can only, of course, be approximately guessed, and with 

 the aid of Comparative Anatomy and Ontogeny. These 

 hypothetic diagrams, therefore, by no means claim to be ac- 

 cepted dogmatically, any more than do those in Figs. 52-56. 

 (Cf. note 85.) 



90 (i. 280). Main incidents in Vertebrate germination. Of 

 the main palingenetic incidents here enumerated, perhaps the 

 sixth, ninth, and tenth originally occurred in a very dif- 



