LETTERING ADOPTED IN ALL THE FIGURES. 



notochord. 



nasal valve. 



oil-globule, o.g. 1. minute aggregated glo- 

 bules. 0. g. 2. larger scattered globules. 



nasal sac. 



opercular flap. 



otocyst. 



embryonic pre-anal fin. 



pigment bar. 



pectoral fin. 



pelvic fin. 



pineal body. 



perivitelline space. 



permanent ventral fin. 



rectum. 



rod-like attachment-process of zona. 



rim of central pedicle of attachment. 



rectal valve. 



dilatation of gut in region of future stomach. 



stratified inner layer of egg-capsule. 



urocyst. 



outer layer of egg-capsule : vitelline mem- 

 brane of Brook. 



yolk. 



yolk-sac. 



zona-radiata. 



EXPLANATION OE PLATE XLVIII. 

 Figs. 13 to 24. 



\The pignmxt, except when otherwise speeijied, is shoicn as by reflected light.'^ 

 Figure. 



13. Ripe unfertilized egg of Rhomlus Imvis. 



14. Fertilized egg of the same (?), advanced, from the tow-net. 



15. Egg of Trachinus vipera, with embryo showing the paired fins {p.f. andpl.f.) connected by a 



continuous ridge {c. r.). Pigment and oil-globules omitted. 



16. Egg of Species V., early stage. 



17. Advanced egg of Species VI. 



18. Egg of Species VII. 



19. Egg of Pleuronectes miorocephahis, with unpigmented embryo. 



20. Part of zona of the same, flattened, Z. D. Oc. 2, Cam. luc. 



21. The same, seen obliquely, in living egg. 



22. Eipe unfertilized egg of Cepola ruhescens : dead. 



23. Egg of Species IV, Ctenolalrus rupestn's. (?) 



24. More advanced egg of the same, more highly magnified. 



[4] 



