Holt — On the Eggs and Larvm of Teleosteans. 437 



SCOMBEID^. 



Scomber scomber (Linn). The Mackerel. 



About fifty small autumn mackerel, from the neighbourhood of Broadhaven 

 Bay, were examined by Mr. Duerden and myself on the 20th June. We found that 

 many of the males were ripe, whilst the females were, in various stages, approach- 

 ing ripeness, with the exception of one which was fully ripe. 



Day* remarks, on the authority of Dunne, that this species spawns at Meva- 

 gissey in May or June ; and Cunninghamf gives June and the first half of July 

 for the Plymouth district. The period seems to extend to August in Scotch waters.:}: 

 Sars found that spawning usually took place in the first half of July. 



TRACHINIDiE. 



Trachinus vipera (Linn.) Tlie Lesser Weever. 

 (PI. XLVii., fig. 8; PI. XLViii., fig. 15; PI. xux., figs. 31, 32; PL l., figs. 37, 38.) 



Ova, which have been identified with this species from Brook's description, § 

 occurred in considerable abundance in the sarface-nets in Blacksod Bay on the 

 15th June and 11th July; in Inver Bay on the 25th, 28th, and 29th June; in 

 Clew Bay on the 30th June ; and on several other occasions in these bays. 



The diameter is 1 '25-1 "37 mm. ; the yolk is clear, colourless, and homogeneous, 

 and there are (fig. 31) from eleven to nineteen small pale greenish-yellow oil globules 

 (the largest "06 mm. in diameter) scattered over the upper hemisphere of the yolk. 

 Seen by the naked eye, the globules give a dull yellowish colour to the egg, very 

 similar to that of the common sole's egg. The egg-capsule is thin, but tough and 

 resistant. 



In flattened preparations, under a high power, an optical section shows that 

 it is divisible into an outer homogeneous layer (fig. 8, v. m.) and an inner layer (^st.) 

 showing four or five stratifications. The two layers are of about equal thick- 

 ness (fig. 8). Treated with picro-carmine, the outer layer takes only the yellowish 

 stain, whilst the stratified part is very faintly affected by the carmine. The double 

 nature of the egg-capsule, in this species, was observed by Brook [op. cit., p. 275), 

 who considers the outer layer as the vitelline membrane, according to the definition 



* Britisli Fishes. Vol. i., p. 89. 



f Eeproduction and deTelopment of Teleostean fishes occurring in the neighbourhood of Plymouth, 

 Journal of the Marine Biological Association. N.S. No. 1, March, 1889, p. 25. 



f Brook. Spawning period of British food-fishes. Eeport Scot. Fish. Board, 1885. 

 § On the development of Trachinus vipera. L. S. Journal Zoology. Vol. xviii. p. 274. 



3 Q 2 



