OCOURRINCt in the neighbourhood of PLYMOUTH. 17 



pigment is confined to the body of the larva and the surface of the 

 yolk ; on the former it is abandant^ especially about the head. 

 The black chromatophores form a fringe at the edges of the median 

 fin, and others are also present on the body and the yolk-sac. The 

 larva is still pei-fectly symmetrical ; no indication of the asymmetry 

 of the eyes and skull is yet apparent. The larva at this stage has 

 a total length of 4*6 mm. 



SOLEA VULGARIS. 



Observing that the ovaries of soles brought in by the fishermen 

 were approaching maturity, I weut out in a trawler on February 6th, 

 1888, to obtain, and to artificially fertilize, some ripe ova. On this 

 occasion, as on many others when I was similarly engaged, the trawl 

 was brought on deck after darkness had set in, and I had to carry 

 on operations by the dim light of a lantern. From one specimen I 

 got a few ova, but could get no milt. The ova, when examined on 

 shore next day, were found to be unfertilized, though two or three 

 were floating. On this occasion the boat, when the trawl was 

 hauled, was about nine miles west by south of the Eddystone. 



My next attempt was on March 6th, when I was on board the 

 " Lola," south-east of the Wolf Rock. At one haul of the trawl I 

 got, out of about thirty-five soles, two or three which yielded a few 

 ripe ova on squeezing, but I could obtain no milt from any of them. 

 On opening those which I judged to be males I found small testes 

 in the usual position, and these I cut out and divided into small 

 pieces, and placed these in the water with the ova, hoping that suffi- 

 cient spermatozoa for fertilization would thus be obtained. This 

 difficulty in obtaining the milt of the sole, an unexpected obstacle to 

 the investigation of the development of the species, occurred con- 

 stantly on every subsequent occasion when I tried to obtain fertilized 

 ova. The cause of it I have not yet discovered. There is no such 

 difficulty in the case of other flat-fishes ; the ova of the merry sole 

 were fertilized with ease, sufficient milt could almost always be 

 obtained by squeezing males, and at other times I have fertilized the 

 ova of P. Jlesus (the flounder), P. limanda (the dab), P. cynoglossus 

 (the witch, or pole flounder) ; but I was not able during the whole 

 of last season ever to squeeze any milt out of a male sole. The 

 probable reason is that the testes of the sole are extremely small. 



On March 7th I examined the soles of another haul with the same 

 result. On my return to Plymouth on March 8th I found only 

 about a dozen of the ova floating, and of these only two or three 

 showed a blastoderm, that is, were fertilized. Thus the pieces of 

 the testes placed in the water had effected fertilization only in a few 



VOL. II, NO. I. 2 



