NOTES ON TELEOSTEAN OVA AND LARVAE. 13 



0"17 mm. for oil-globule, which was frequently of a yellowish tint. 

 The species may be readily recognized towards the end of embryonic 

 development by the characteristic yellow and black pigmentation. The 

 yolk is homogeneous, the oil-globule of a yellowish tint, and the 

 capsule marked with fine corrugations. At about the time of the out- 

 growth of the caudal rudiment black chromatophores appear on the 

 head and in a line on either side of the body. A rather large Kiipfer's 

 vesicle is visible at this stage. Yellow pigment appears soon after- 

 wards. One larva soon after hatching measured 1'40 mm. from snout 

 to anus, and about 2'46 mm. in total length. Another had a total 

 length of 2'02 mm., the distance from snout to end of yolk-sac being 

 1"08 mm. Black and yellow pigment occurs in rather large, stellate or 

 dendritic chromatophores on the head and along the sides of the 

 body. At about the level of the anus and in the mid-post-anal region 

 there is a tendency for it to be more concentrated. The embryonic 

 fins and the posterior extremity of the trunk are unpigmented. 



In spite of the abundance of pelagic ova not a single larval or post- 

 larval specimen occurred in our young-fish trawl collections. The 

 young fish appear to seek early the deeper parts of the Channel. The 

 only specimen recorded up to the present is one of 15^ mm. length, 

 taken in September, 1906, by the Danish research steamer I'ltor, to 

 the west of the Channel Islands (21d, p. 5). 



Trachinus vipcra, Cuv. 



This conspicuous and very easily identified egg occurred frequently 

 though not abundantly in our samples from the latter part of May to 

 the end of August. The many bright yellowish-green oil-globules 

 and the richly pigmented embryo and yolk-sac render it a conspicuous 

 object in the tow-nettings. The diameter lay between 1-28 mm. (in 

 May and June) and I'l mm. at the end of August. Post-larval stages 

 were frequently taken from the end of June throughout the summer. 



Trigla. The Gurnards. 



There are five species of Trigla occurring in the waters off Plymouth, 

 and the specific identification of their pelagic eggs, which are similar 

 in character and show considerable overlapping in dimensions, is a 

 matter of great difficulty and often an impossibility. The only circum- 

 stances which ensure certainty of determination are when the spawn- 

 ing fish are captured in quantity at about the same time and in the 

 same area as the eggs, so that an extensive comparison can be made 

 between tlie planktonic eggs and those taken from tlie ripe fish. 



