4* 't 



1 ection through the 



! i illustrated in the three pre- 



Lcrossthe 

 middle of i the ] pal embryo, 



■ . 



ion, and 



lin, Ml 



three ; x '" ■ ■ eparate, 



egion of 

 '' ' 



a well- 

 developed head-kid;: 



princip es some 



'i .tarn ■ eferences 



i" given under Fig, 94, 1 ■ 10.) 



Fig, 98.— 1 ransverse section belonging 

 to the same sei ies ,1- the last figure, but .1 

 little further back. The body of embryo 

 . / is taken up chiefly with the nerve tissue 

 ol the medulla and spinal cord, while B 

 don 01 ih" tiny fourth venti icle 

 and medulla. Below the bodies of A and 

 /■' are seen the Wolffian ducts, air-sai , 

 stomachs, and the hepatic tissue In l< 

 ing to these embryos. A pelvic fin of the 

 principal embryo comes into the section 

 on its left side. Other references are given 

 undei I ig. 94. ( ■ 14-) 



FlG. 99. — Trans vi 1 -■■ ■-.. . don from same 

 sei ies as the la t two figures, but a con- 

 siderable distance further back. The 



of the two defective embryo 

 now uniting, and they are seen to be 

 made up ol very irregular tissues, the 

 spinal cords being recognisable. 



I hi intestinal can ah ol thi 

 are joining together, the pai t seen 

 the middle being the commencement of 

 tti<- ci minion terminal portion. References 

 94. 1 ■ 17.) 



PL. XXIII. 



