THE HERRING FAMILY. 433 



The Twaite-Shad. (Glupea finta, Cuv.) 



The eggs of this ally of the herring are deposited in fresh 

 water, the fishes entering rivers for this purpose; thus the 

 adults are occasionally procured in the Tay and other British 

 rivers in spring. Ehrenbaum observed that the eggs when 

 shed. (at night in the end of May) were 1"5 to 16mm. in 

 diameter, but as in the other species, the perivitelline space 

 gradually enlarged till the diameter reached 4'2 to 4'6 mm. 

 They hatched, at a temperature of 66°, on the fourth day. The 

 reticulated yolk and other features corresponded with the 

 previous species. 



The newly-hatched larva is about ^ of an inch long, with only 

 traces of pigment. When 8 to 9 mm. long the yolk was almost 

 absorbed, and the mouth functional. At 15 mm. the body was 

 elongated and slender, with large otocysts, traces of permanent 

 rays in the fins and tail, and with the black pigment best 

 developed along the ventral edge of the muscle-plates. At the 

 end of June those of 16 to 20 mm. had forked tails, a clupeoid 

 outline, but no scales. On 6th July they were from 24 to 29 

 mm. in length and slightly silvery. They reached 36 to 46 mm. 

 in the middle of July with scaled and silvery sides, the dorsal 

 fin in front of the pelvics, and with well-developed pigments 

 Ehrenbaum found the eggs of the twaite-shad in the Elbe 

 in May with advanced embryos. Towards the end of the 

 month he captured larvae from 8 to 9 mm. Yarrell and Day 

 give June and July as the spawning-period in our rivers, the 

 latter having opened several in the Severn on June 3rd and 

 found the eggs almost ready for deposition. Yarrell obtained 

 the young 2^ inches long in October, and 4 inches the following 

 spring. 



Ehrenbaum, again, captured young twaite-shads from 

 1'68 in. to 4'96 in. from August to the middle of November, 

 and concluded that these were the young of the previous 



' Abstract from Mr Cunningham's remarks, Market. Fishes, pp. 180 and 

 181. 



M. F. 28 



