NOTES ON TELEOSTEAN OVA AND LARVAE. 41 



parent fish Phycis hicnnoidcs, a rare visitor to this coast and one which 

 had probably arrived in the track of the shoals of mackerel and scad 

 (Caranx trachurus), which were present in unusual abundance in the 

 inshore waters at the time of his Plymouth observations. Since that 

 time, there have been no observations of planktonic fish eggs in the 

 summer months here until the present year, so that the solution of the 

 question as to whether the eggs belonged to a constant or intermittent 

 visitor to these shores by the plan of noting the presence or absence 

 of the eggs in successive years, has not been possible. It so happens 

 that the present summer (1909) has also been characterized by a 

 greater than usual abundance of mackerel and scad in the inshore 

 waters of the Plymouth area, but whether this condition can be cor- 

 related with the presence of these eggs is doubtful. Heincke and 

 Ehrenbaum (10, p. 258) have subsequently observed the egg as 

 regularly occurring with summer plankton off Heligoland, and since 

 Phycis Mennoides, the only other fish to which it could with any prob- 

 ability be ascribed, is never found in Heligoland waters, they have 

 identified it with Eaniays rani/iiis—8i quite well-founded conclusion, 

 although the absolutely unquestionable identification by tracing back 

 the egg to the parent still remains unaccomplished, since the ripe 

 female is as yet unknown. Holt's Irish specimen measured 0.775 mm. 

 and had a colourless oil-globule of 014 mm. diameter. The larva 

 about twelve hours after hatching measured 2'68 mm. Those taken 

 by him at Plymouth at the end of June and in July measured from 

 0"84 to OOl mm. in diameter, and the diameter of the oil-globule ranged 

 from 016 to 017 mm. In August the dimensions were 078 to 0*84 

 mm. for eggs and 015 to 017 for oil-globule, and a newly hatched larva 

 was 2*02 mm. in length. The Heligoland eggs had a diameter of 0755 

 to 0"912 and an oil-globule from 0141 to 0189 mm. in diameter, while 

 the length of newly hatched larvae varied from 2*26 to 2*90 mm. 

 The dimensions of my specimens were as follows : — 



Diameter of egg . . 0-80, 0-78 x 079, 0-81 x 0-84, 0-82. 

 „ oil-globule 0145, 0145 0165 0157. 



Two of them were ovoidal. The yolk is homogeneous, and the oil- 

 globule is colourless. Just before the formation of the caudal rudiment, 

 the head and body are liberally covered with medium-sized, black 

 chromatophores, and yellow is making its appearance along the sides of 

 the embryo. On the yolk-sac there is pigment of both colours, which 

 is most dense in the postero-ventral region, a feature becoming more 

 strongly marked as development proceeds. In the two larger specimens 

 there are black and yellow chromatophores over the oil-globule, but 



