in the Foetus of Vertebrated Animals. 307 



A German author, Funk*, who has written an interesting 

 memoir on the structure and development of the Land Salaman- 

 der (an ovo-viviparous animal), has made in it an observation 

 corresponding with that related above on the development of the 

 bloodvessels in the water newt. " Permulta vasicula tenuia,'' 

 says this author, " inter se complicata, a parte dorsali exorta in 

 vitello evanescentia in conspectum veniunt ;" showing in this re- 

 spect the analogy subsisting between the salamander and other 

 animals (Fig. 17, A:). It may be remarked, however, that this 

 animal possesses a distinct yolk-bag. 



4. Clianges of the Germinal Membrane in Fishes. 



In the ova of cartilaginous fishes, such as the skate and shark, 

 the yolk is of a large size, and is filled with a white granular 

 and oily matter. The cicatricula, lying on the . surface, is 

 small, and resembles considerably the same part in the egg of 

 the bird. 



The ova of osseous fishes are generally small and transparent. 

 From the observations of Cavolini-|-, on the development of the 

 Syngnathus ophidion, the Cyprinus barbus, and some other os- 

 seous fishes, and of Forchhammer | and Rathke§ on that of the 

 Blennius viviparus, it appears that the elements of the germinal 

 membrane in the ova of osseous fishes are the same as those we 

 have described in the egg of the bird, and that the changes by 

 .which the organs are formed from these parts are, in many re- 

 spects, analogous. 



The germinal membrane, which, even before development has 

 commenced, appears to occupy a considerable space on the sur- 

 face of the yolk, first increases in size and expands laterally, 

 (Fig. 2 c). It then becomes thicker in the centre, and the primitive 

 trace appearing in the serous layer (Fig. 1, 6), is surrounded by 

 the spinal canal. The head, tail, and vertebral column are soon 

 distinguishable, as well as the rudiments of the intestinal canal 

 communicating with the sac of the yolk. The rudiment of the 

 heart is first perceived between the anterior or oesophageal por- 



• De Salamand. terrest. Vita evolutione, &c. Berolini, 1827. 

 •j- Die Erzeugung der hartgrStigen Fische. Berolird, 1792. 

 X De Blennii Vivip. forniatione et evolutione, iScc. Kiliae, 1819. 

 § Gesehichtu des Embryo der Fische, in Burdach's Work, vol. ii. 



