NOTES ON TELEOSTEAN OVA AND LARVAE. 33 



Gadus minutus and Gadus luscus. 



Oil 8th April a ripe female G. minutus was taken in the trawl 

 about 7 miles south-west of the Eddystone. Eleven ova from 

 this measured 0'91-1"02 mm., the average diameter being 0-939 

 mm. Artificial fertilization was attempted, but development was 

 stopped by death at the blastula stage. Eight eggs taken in the 

 tow-nets on the same day and in the same locality had diameters 

 of 0-94, 1-08, 1-09, 1-13, 1'14 (two eggs), and 1-13 x 117 mm. 

 (the last not exactly spherical). The embryonic form of all appeared 

 practically identical. Eound and dendritic black chromatophores first 

 appear on the embryo, and at a later stage a diffuse yellowish tint 

 appears over both embryo and yolk-sac. Just before hatching the 

 black chromatophores are most densely distributed in the posterior 

 half, and there is little or none of this pigment on the head. One or 

 two black stellate chromatophores usually appear on the yolk-sac,* to 

 which also outgrowths from the pigment cells in the otocystic region 

 generally extend. The head and anterior part of the embryo are 

 covered with a diffuse greenish yellow tint ; the yolk-sac occasionally 

 shows distinct yellow chromatophores at this stage, but more usually 

 is also diffusely tinted. Only once I noticed distinct chromatophores 

 on the embryo before hatching. I noted no pigment on the embryonic 

 fin at this stage. Two larvae hatched out from eggs of I'UB and 

 1-09 mm. diameter measured (a) 2-65 mm., of which 1-35 mm. was the 

 pre-anal length, and (b) ca. 2*9 mm. with a pre-anal length of ca. 1"5 mm. 

 A tliird larva, (c), slightly more than twenty-four hours old, measured 

 2-9 mm. total length (1-2 mm. from snout to anus). This was from 

 the egg of 1-13 x 117 mm. diameter. A fourth larva, (d), from the 

 egg of 114 mm. diameter, measured when the yolk was absorbed, had 

 a length of 3 mm., of which 1"28 mm. was pre-anal. The pigmentation 

 consists of black chromatophores mostly dendritic, distributed along 

 the dorsal and ventral contours, in the peritoneum, a little on the top 

 of the head and about the pectoral region. In specimen (a), however, 

 the pigment extends to the tip of the caudal region, while in (b), 

 which has heavier pigmentation, the last 0"3-0-4 mm. of the tail is 

 bare. 



This difference, considered together with the difference of larval 

 size, suggests a difference of species which was impossible to detect in 

 the two eggs so similar in general character and only differing by 

 0-01 mm. in diameter. From which egg each larva was produced I 



* Tliis was noted on eggs wliich gave lise to different types of larvae, e.g. (a) and (b). 

 See above. 



NEW SERIES. — VOT,. T.\. No. 1. OGTOHEIL, 1910. C 



