EMBRYOLOGY AND LARVAL DEVELOPMENT OF TELEOSTEAN FISHES. 9I 



aa. Eggs with oil globules, spherical in form. 



/. Egg with one (rarely two) oil globule. 



g. Egg with very large perivitelline space; diameter of egg 1.4 to 1.6 mm., of yolk sphere 

 0.9 to 0.93 mm.; cortex of yolk sphere segmented; oil globule small, 0.12 to 0.14 

 mm. in diameter; pigmentation begins several hours after closure of blastopore; 

 at time of hatching small black pigment spots are more or less closely aggregated on 



upper surface of head and body Brevoortia tyrannus (menhaden) . 



gg. Egg without large perivitelline space. 



h. Egg 0.7 to 0.8 mm. in diameter; a single large oil globule 0.17 to 0.2 mm. in diameter 

 or two smaller ones which later coalesce; in well-differentiated embryo black 

 chromatophores are sparsely scattered over its entire surface, on extra-embryonic 

 blastoderm and oil globule, being relatively large at time of hatching. 



Poronotus triacanthus (butterfish). 

 hh. Eggs 0.85 to I mm. in diameter. 



». Oil globule transparent, small, less than 0.18 mm. in diameter. 



j. Egg 0.85 to o.g mm. in diameter; pigmentation first observed in embryos of 



15 to 20 somites; black and yellow pigment cells sparsely scattered over 



embryo and oil globule, and these increase in number and size; before 



hatching the yellow chromatophores have become aggregated to form heavily 



pigmented areas Sienotomus chrysops (scup). 



jj. Egg o.g to I mm. in diameter; oil globule about 0.125 mm. in diameter (Sienna 



flounder of Agassiz and Whitman) Species(?) 



a. Oil globule opaque, yellowish or brownish in color, 0.19 to 0.23 mm. in diameter; 

 pigmentation appears shortly after closure of blastopore; black chromatophores 

 become sparsely scattered over embryo and oil globule, those on posterior part 

 of body later becoming aggregated in two vertical bands; yellow pigment 

 behind eye, back of otocyst, along side of trunk anteriorly, and in the two 



vertical bands MerVuccius bilinearis (whiting). 



ff. Oil globules several to many. 



k. Egg 0.7 to 0.8 mm. in diameter; one or more large oil globules and numerous 



small ones Urophycis chuss (hake). 



kk. Egg I to 1.35 mm. in diameter. 



/. Egg I to 1. 15 mm. in diameter, slightly yellowish in color but highly trans- 

 parent; 10 to 25 unequal oil globulespresent; numerous yellow and black 

 pigment cells are present over entire surface of embryo and extra-embryonic 

 blastoderm, before hatching becoming fewer and more scattered. 



Prionotus carolinus (sea robin). 



II. Egg with two to five (rarely one) large oil globules and several smaller ones 



egg 1. 15 to 1.3s mm. in diameter, transparent Sarda sarda (bonito); 



II. Demersal eggs. 



m. Eggs attached by adhesive threads arising from egg membrane. 



n. Adhesive threads arising in a tuft from one point on egg membrane. 

 o. Egg yellowish, semiopaque, I.I to 1.2 mm. in diameter; 5 to 12 large, 

 oil globules of unequal size and numerous smaller ones present; 

 black chromatophores become sparsely scattered over embryo and 

 blastoderm, followed by yellow ones on embryo; later black ones 

 become aggregated in a few areas on top of head, in series along 

 base of ventral-fin fold, and a few at base of dorsal-fin fold pos- 

 teriorly Menidia menidia notata (silverside). 



00. Egg tinted with yellow, more transparent than preceding, 0.9 to 

 I mm. in diameter; one or two large oil globules and few smaller 

 ones; fewer adhesive threads (four to six) in tuft than pre- 

 ceding Menidia beryllina cerea (silverside). 



nn. Adhesive threads scattered over surface of egg membrane. 



