166 



MR. E. W. SHANN ON THE EMBRYONIC 



same time the notch on the inner border of the upper lobe is 

 distinctly visible). 



The ground-colour is slate-grey fading to cream underneath 

 and upon the paunch. The skin in the younger examples 

 (350 mm.) is perfectly smooth, but in sliglitly larger ones (430 to 

 450 mm.) there is a slight I'onghness due to the developing 

 scales. The skin passes without interruption from trunk to 

 paunch (i.e., without the deep crease which the illustration seems 

 to indicate). 



Table II. shows the detailed measurements of a series of 

 embryos. The outstanding featui-e of this Table is the clear 



Table II. 

 (x\ll measiu'ements are in millimetres.) 



Index (see TaWe I.) 



F 



H 



Length 



V 11 i. 1 ( long axis 



Yolk-stomach I ^j^^»^ ^^^..^ 



Diameter of Eye 



Tip of Tail to Yolk-stomach 



Anterior of Cloaca to Root of Tail 



Snout to 1st Dorsal Fin 



1st Dorsal to 2nd Dorsal Fin 



Pectoral to Pelvic Fin 



Pelvic to Anal Fin 



C base 



1st Dorsal Fin 



I height . 



Pectoral Fin {J;;-^^ ";;;;;;;;; 



Pelvic Fin{f^,^^^^J»-''^"^;;';;-^f^^^^ 



Caudal Fin ( upper lobe 



(outer rim) ^ lower lobe 



350 



105 

 52 



6 ' — 



95 



125 



107 



90 



55 



25 

 17 



20 

 36 



10 

 20 



115 



45 



454 



200 

 135 



11 



100 

 1G6 

 159 

 120 



44 

 30 



26 

 67 



11 



29 



145 



75 



553 



211 

 123 



12 



267 



178 



178 



131 



65 



43 

 32 



30 



54 



16 

 29 



147 



82 



605 



14 



'125 

 220 

 203 



57 

 52 



40 



21 

 35 



168 



demonstration that the paunch (due to the pi-esence of the yolk- 

 stomach) increases in bulk as the fish grows in size ; we are 

 thus forced to conclude that growth at this stage is not due 

 to the use of reserve material, but to some external cause. The 

 other measurements, apart from a few discrepancies (accountable 

 either to normal variation or to individual methods on the part 

 of different observeis), give a very fair representation of normal 

 growth. 



In the male specimen of 350 mm. the claspers of the jielvic 

 fins are manifest even to a casual glance. The fins themselves 

 showed the same measurements as those of the female twin (F). 



