‘of the Fishery Board for Scotland. Mn 
‘DESCRIPTION OF PLATES. 
The figures, except figs. 16 and 17, were drawn by means of fine camera 
I cida. & 
Reference Letters. 
:. a.c. \alimentary canal. ms. somites. : 
XS a pus. m.c. neurenteric cgnal. 
i. au. & | no. notochord. g 
D b. blog. ou? eye. , 
f br. brai ol.o. olfactory @rgan. 
i. 6.0. branchial aorta. p.b. pineal bgfly. 
4 bv. blood-végsel. p.r. pigmengflayer of retina, 
4 ¢ claspers. 4% r  retina.g 
e  epiblast. % s.t, sensomy - tubes. 
ie ept. epithelium.% | sp. — spiradfle. 
a eg. external gill. t. tail 
e g.c. gill clefts. L u.c. ungpilical cord. 
q ht. heart. | u.f. ‘aipaired fins. 
i hy. hypophysis. v.  t#igeminus nerve. 
7. l. lens. " vit. Sacial nerve. 
* m. site of mouth. | 3 vii. auditory nerve. 
* mc. medullary canal. . ix. # glossopharyngeal nerve, 
4 me.c. mesoblast cells. | x. @ vagus nerve. 
4 me. merocytes. % if 
i. f e 
ee Fig. 1. Superficial segmentatio} 
ie Fig. 2. Deep segmentation. 
i Fig. 3. Shows segmentation cavit} fin section. 
" Fig. 4. Entire blastoderm of pregdipg stage, aged thirty-one days, 
‘ Fig. 5. First embryonic thickenjiig, Myrty days. 
P Fig. 6. Embryo of fifty-four dags (win'gr). 
Fig. 7. Embryo of ten weeks finter). 
Fig. 8. Embryo of eleven andgi half week (winter), 
ig. 9. Embryo of twelve wefks (winter). 
ig. 10. Embryo of about tw@lve weeks (wint@). 
ig. 11. Embryo of nearly fg@irteen weeks (winfgr). 
. 12. Embryo of fourteey weeks (winter). 
ig. 13. Embryo of thirteeg§ and a half weeks (sprigg), length 5:8 mm. 
ig. 14. Embryo of eleverfweeks (early summer), leh c= 75 mm. 
ig. ae Head end of emiifyo of 2. clavata. 
. 16. Dorsal view of embryo of six months, life size. 
. 17. The same as segh from the ventral aspect. 
ig. 18. End of an extefnal gill-filament of an embryo twery-three weeks 
old. x 60 fiameters. % 
All the fi jures, except fig. 1b, refer to R. batis, % 
