NOTES AND MEMORANDA. 



397 



backwards towards the caudal peduncle, and are strongly notched 

 at intervals. Each notch marks the site of one of the finlets of the 

 adult, but at the present stage it is occupied only by a single stout 

 ray. There are five such isolated rays in the anal fin of the specimen 

 of 16*5 mm. (in which the fins are the most expanded), thus corre- 

 sponding in number to the finlets of the adult. 



The colours in spirit specimens are as follows : — In the largest 

 specimen the eye, gill-cover, and sides of the abdomen are silvery. 

 There is a large deep black patch on the top of the head, due to 

 pigment in the pia mater of the optic lobes ; some smaller black 

 patches occur on the snout, jaws, and isthmus. There is a dark 

 line along the dorsum and at the base of the anal fin. From these 

 lines dark pigment dots extend along the myomeres to the lateral 

 line, the region of which is thickly powdered with such dots. The 

 two smaller specimens differ only in exhibiting less pigment on the 

 sides of the body, very little being present in the smallest, in which 

 also the silvery matter is so little developed as to allow the black 

 peritoneal pigment of the abdominal roof to be clearly visible. 



In the early part of the same month I took at the surface a few 

 much smaller fish, to which at the time I devoted little attention 

 beyond noting the light blue colour of the eye, and the presence of 

 yellow amongst the black pigment of the top of the head and abdo- 

 men. They are all rather badly injured, but the larger amongst 

 them, about 9'5 mm., approach the smallest of the series previously 

 described in the shape of the head and the distribution of black 

 pigment. The permanent dorsal and anal fins are not yet repre- 

 sented, so afford no assistance. The differences in the proportions 

 of the pre- and post- anal regions are not more than might be ex- 

 pected in the same species at such different stages. The smallest 

 specimen sufficiently well preserved to be of any use measures 

 7 mm., and while certainly belonging to the same species as that 

 of 9'5 mm., it also approaches the oldest stage to which I have been 

 able to rear mackerel larvae from the egg. The largest of such 

 measures 4'88 mm., and the black pigment differs from that of the 

 tow-net specimens only in quantity, and not in distribution. The 

 large light blue eye, and the presence of yellow pigment in the 

 regions indicated above, are features which both series possess in 

 common. 



Though, owing to the bad condition of the smaller tow-net speci- 

 mens, absolute proof is wanting, I think it very probable that they 

 are really mackerel. They were taken on the 8th July, about 

 twenty miles N.N.E. (magnetic) of the Horn Reef Light-vessel, 

 coast of Jutland. The locality and date of the larger specimens are 

 mentioned elsewhere by Mr. Cunningham. — E. W. L. H. 



