LETTERING ADOPTED IN ALL THE TIGUEES. 



notochord. 



nasal valve. 



oil-globule. 0. 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 OF PLATE LI. 



Figs. 40 to 45. 



\The pigment, except when otherwise specified, is shoivn as by reflected light. 1 

 Figure 



40, 41. Newly-hatched larva of Callionymus lyra. Ventral and profile views. 



42. Larva of the same, about twelve hours old. 



43. Larva of Species V., shortly after hatching. 



44. The same larva, one day older. 



45. Part of notochord of the same, more highly magnified. 



[10] 



