278 PROCEEDINGS OP THE AMERICAN ACADEMY 



of the stomach, and three lines of rectangular pigment cells extend- 

 ing, the one along the whole base of the embryonic anal, the second 

 along the lateral line, the third along the base of the posterior ex- 

 tremity of the embryonic dorsal. The next stage figured (Plate X. 

 fig. 2) is characterized by its proportionally larger head, by the pres- 

 ence of a large dendritic pigment cell over the base of the brain, with 

 five rounded spots in front of it over the principal lobe of the brain, 

 and similar spots behind extending into the dorsal line of pigment 

 spots, which in this stage runs along the whole base of the embryonic 

 dorsal, and forms a line fully as marked as the other two already 

 existing in the younger stage. In this stage the yellow coloring of 

 the body is more intense along the upper part of the head, over the 

 stomach, and along the dorsal line, than in the younger stages. The 

 large dendritic pigment cells on the top of the head are sometimes 

 found in specimens quite as young as Plate X. fig. 1. In the stage 

 of Plate X. fig. 2, the caudal fin is forming. 



In the next stage figured (Plate X. fig. 4) the head has become 

 somewhat lengthened, the caudal fin more terminal, the embryonic 

 caudal lobe quite rounded ; the yellow coloring of the body and head 

 is more marked, and has assumed at the same time a somewhat green- 

 ish tinge. The embryonic dorsal and anal are slightly lobed ; the first 

 trace of the base of the permanent dorsal and anal rays can be seen 

 along the dorsal and ventral lines. There are very rudimentary ven- 

 trals as slight projections, one on each side of the anterior part of the 

 embryonic anal. The diagonal muscular bands are well marked. 

 The three lines of pigment cells are more prominent than they were 

 in the preceding stage. 



In a somewhat older stage (Plate XI. fig. 5) the head is propor- 

 tionally more elongate than in younger stages. The caudal fin is 

 nearly symmetrical, but with a slight trace of the embryonic caudal 

 lobe ; the dorsal and anal are well separated from the caudal ; their 

 permanent fin rays have commenced to form, though not as well 

 advanced as those of the caudal. 



In the next stage figured, when the young Atherina has attained a 

 length of about 16"^™ (Plate XL fig. 6), the general outline of the 

 head and body is much that of the adult ; but the tail fin is still 

 rounded ; there is but a trace of the anterior dorsal ; the dorsal and 

 anal are still quite low, though completely separated from the caudal ; 

 the anterior part ot the anal embryonic fin, in which no permanent 

 rays are formed, has not entirely disappeared ; the ventrals have 



