14 EEPRODUCTION AND DEVELOPMENT OF TELEOSTBAN FISHES' 



and some other species, but those of the former were unfertilized. 

 He went out again on May 8th, this time on board tlae " Lola/^ to 

 the Mount^s Bay ground, and returned on May loth, bringing some 

 fertilized ova of this species. I did not stay on shore to study 

 these, as I was anxious to go out myself to procure soles' ova, and 

 went to sea on May 15tli for this purpose. On this occasion I 

 did not get ova of PI. microcephalus. On May 26tli some healtliy 

 fertilized ova of this species were sent up by the captain of the 

 *' Lola ;" they were taken near the Wolf Rock on May 24th. The 

 Laboratory fisherman, William E-oach, obtained more ova of the 

 same species on May 29th on a trawler to the south of the Eddy- 

 stone, and this was the last lot that I received. 



It thus appears that the species we are considering spawns during 

 April and May, the period, no doubt, extending in the case of a few 

 individuals slightly beyond these limits in either direction. 



A few data were obtained to indicate the physical conditions to 

 which the ova are normally exposed. The density of the water 

 in the neighbourhood of the Eddystone is r0267 to r0269 (see 

 under Scomber). 



On April 7th I brought a clean sample of sea-water from where 

 we had been fishing, south of the Wolf Rock, in a stoppered bottle, 

 and found its density when tested in the Laboratory was ]*0270. 

 The temperatures observed were as follows : 



April 4th.— South-east of Wolf Rock . 

 „ 12th. — 5 miles south of Eddystone 



„ 16th.— Ditto 



„ 25th. — 40 miles north of Longships Lighthouse 



May 10th. — 10 miles south-east of Wolf Rock . 



„ 29tli. — 6 miles south-west of Eddystone 



Surface 

 Surface 



Bottom, 40 f ms 

 Surface 

 Surface 

 Bottom, 50 fms 

 Surface 



Bottom, 45 fms 

 Surface 

 Bottom, 40 fms 



2°C. 

 6°C- 

 5°C. 

 7°C. 



2°C. 

 0°C. 

 9°C. 

 4°C. 



■8°C. 



In describing the artificial conditions undtr which the ova were 

 kept in the Laboratory, I shall consider first and more fully those 

 obtained on April 12th about five miles south of the Eddystone, as 

 from these all the figures and most of the description given below 

 of the development were taken. 



When these ova were brought in I transferred them to some 

 water taken a short distance from the shore opposite the Laboratory ; 

 the density of this was 1*026, and the ova all floated in it without 

 difficulty, remaining in a layer at the very surface. They were 

 simply left in jars of the water, Avith no arrangement for continuous 



