OF ARTS AND SCIENCES. 301 



Fig. 3. Slightly older than preceding stage. Eudiments of anterior dorsal 

 spines and of ventrals have made their appearance, 15"'™ in length. 



** 4. In this stage the rudimentary anterior dorsal spines, as well as ventrals, 

 have increased somewhat in length, the dorsal and anal are both 

 higher, and the chromatophores of the body are arranged in bands 

 somewhat as in the adult, 22™"^ in length. 



" 5. Young Gasterosteus, in which the principal characteristics of the adult 

 are fairly developed, 27™™ in length. 



" 6a. Anterior spine of ventral of young Gasterosteus, somewhat older than 

 preceding stage. 



PLATE X. 



Athekinichthys not ATA, Guntli. (Chirostoma, GilV). 



Fig. 1. Young Atherina measuring 5™™ in length. 

 " 2. Somewhat older stage, measuring 6.5™™ in length, seen from above. 

 " 3. About in stage of fig. 2, seen in profile. 

 " 4. Older than preceding stage, 9™™ in length. 



PLATE XI. 



Athekinichthys not at a, Gunth. 



Fig. 1. Somewhat more advanced than preceding stage (Plate X. fig. 4) 10, 5™»^ 



in length. 

 " 2. Young Atherina measuring 16™™ in length. 

 " 3. Young Atherina, having the principal characters of the adult, of about 



the same length as fig. 2. 



PLATE XIL 



OSMERUS MORDAX, Gill. 



Fig. 1. Young Osmerus just hatched, measuring 5™™ in length, seen in 



profile. 

 " 2. Same seen from above. 

 " 3. Young Osmerus measuring 9™™ in length. 

 " 4. Considerably older than fig. 3 ; 22™™ in length. 

 " 5. Oldest Osmerus found swimming on the surface, measuring 22™™ in 



length. 



PLATE XIIL 



Ctenolabrus cceruleus, Dek. 



Fig. 1. Young just hatched from the egg, 2™™ in length. 

 " 2. Young, on the second day after hatching, 3™™ in length. 

 " 3. Young on the third day after hatching. 

 " 4. Young on the third day after hatching, somewhat older. 

 " 5. Young hatched four days, about 4™™ in length, seen in profile. 

 " 6. Yoimg same as fig. 5, seen from above. 



