4$4 NOTES. 



series was perhaps transmitted from the Chorda Animals even as 

 far as the lower stages of Vertebrate ancestors. Cf . Chapter XXV. 



146 (ii. 89). I am inclined to regard the Appendicularia as 

 living Chorda Animals of the present day ; they are the only 

 Invertebrates permanently possessing a notochord, and thus, as 

 by many other peculiarities, distinguished from genuine Tuni- 

 cates. 



147 (ii. 105). Metamorphosis of Lampreys. That the blind 

 Ammocoetes change into Petromyzon was known two hundred 

 years ago (1666) to the fisherman Leonhard Baldner of Stras- 

 burg ; but this observation remained unrecognized, and the 

 modification was first discovered by August Muller in 1854 

 (" Archiv fur Anat.," 1856, p. 325). Cf. Siebold, "The Fresh- 

 water Fishes of Central Europe" ("Die Siisswasserftsche von 

 Mittel-Europa," 1863). 



148 (ii. 114). Selachii as Primitive Fishes. The old disputes 

 as to the systematic position and kindred of Selachii were first 

 definitely settled by Gegenbaur, in the introduction to his classical 

 work on " The Head-skeleton of Selachii." 



149 (ii. 118). Gerard Krefft, "Description of a Gigantic Am- 

 phibian ; " and Albert Giinther, " Ceratodus, and its Systematic 

 Position." — "Archiv fur Naturgeschichte," 37, 1871, vol. i. p. 

 321 ; also "Phil. Trans.," 1871, Part II. p. 511, etc. 



150 (ii. 129). The duration of metamorphosis of Amphibia 

 varies much in the different forms of Frogs and Toads, the whole 

 forming a complete phylogenetic series from the original, quite 

 complete form, to the later, much shortened and vitiated heredity 

 of modification. 



151 (ii. 129). "All the histological features of the Land 

 Salamander (Salamandra metadata) force the impression that it 

 belongs to an entirely different epoch of terrestrial life than that 

 of the Water Salamander (Triton), externally so similar."' — Robert 

 Remak (" Entwickelung der Wirbelthiere," p. 117). 



152 (ii. 130). Siredon and Amblystoma. Yery various views 

 have lately been expressed as to the phylogenetic significance to 

 be attributed to the much-discussed modification of the Mexican 



