

X 





■ 



of the Fishery Board for Scotland. 



DESCRIPTION OF PLATES. 



The figures, except figs. 16 and 17, were drawn by means oj'the camera 

 l^cida. 



Reference Letters. 



ilimentary canal. 



ms. 

 ei 



b. bio! 

 br. brainl 

 b.o. brancflkil aorta. 

 b.v. blood- vqfcsel. 



c. claspers. 

 e. epiblast. 

 epi. epithelium/ 

 e.g. external gill/ 

 g.c. gill clefts. 

 ht. heart. ' 

 hy. hypophysis. 

 I. lens. 

 m. site of mouth. 

 m.c. medullary canal. 

 me.c. mesoblast cells. 

 me. merocytes. 



somites. 



neurenteric c#nal. 



notochord. 



eye. 



olfactory Jrgan. 



pineal b<my. 



pigmenj^layer of retina. 



retinaJ 



sensoj# tubes. 



spira#e. 



taiLj 



um»ilical cord. 



uapaired fins. 



igeminus nerve. 



tcial nerve, 

 luditory nerve* 

 glossopharyngeal nerve, 

 vagus nerve. 



Fig. 

 Fig. 

 Fig. 

 Fig. 



Fig. 

 Fig. 



Fig. 

 Fig. 

 Fig. 



1. Superficial segmentation 



2. Deep segmentation. 



3. Shows segmentation cavitWin section. 



4. Entire blastoderm of preditfcag stage, aged thirty-one days. 



5. First embryonic thickenmg, l%rty days. 



6. Embryo of fifty-four daJs (winrnr). 



7. Embryo of ten weeks (Minter). 



8. Embryo of eleven andJi half weel3^( winter). 



9. Embryo of twelve wt»ks (winter). 



10. Embryo of about twflve weeks (wintl 



11. Embryo of nearly fourteen weeks (win^r). 



12. Embryo of fourteew weeks (winter). 

 Embryo of thirtee* and a half weeks (sprl 



Tweeks (early summer), lei 

 Fyo of R. clavata. 

 ibryo of six months, life size? 

 from the ventral aspect. 

 End of an external gill-filament of an embryo twen%y-three weeks 

 old. x 60 fliameters. 



Embryo of elevei 

 Head end of eml 

 Dorsal view of 

 The same as sei 



j), length 5*8 mm. 

 jth 7 '5 mm. 



All the figures, except fig. 15, refer to R. batis. 



