THE GURNARD FAMILY 



331 



colour gradually disappears. Mr. Holt has observed that there 

 are often two or three oil globules in the eggs as they come 

 from the fish, but they usually unite into one in a very short 

 time. 



At Plymouth the eggs of the red gurnard hatched in six 

 days : at a lower temperature at St. Andrews those of the grey 

 took thirteen days to hatch. The newly hatched larva of the 

 red gurnard is 37 mm. in length (not quite ^V inch). The 

 intestine ends close behind the yolk-sac, in which the oil globule 

 is at the hinder end. The 

 mouth is not open : the rudi- ^ ^ 



ments of the breast-fins are 

 unusually large. The pigment 

 is black and orange, and is 

 present over the body and 

 yolk-sac, and along the edges 

 of the longitudinal fin-mem- 

 brane. 



The larvae of the grey gur- 

 nard were kept alive in aquaria 

 at St. Andrews by Prof. 

 Mcintosh for three weeks 

 after hatching. At the end of 

 this time they were about 6 

 mm. (t/V inch) long, and the 

 yolk was absorbed. Only fine 

 primitive fin-rays were present 

 in the breast-fins, none in the longitudinal fin-membrane. 



A succession of later stages were obtained by the tow-net in 

 St. Andrews Bay at 23 fathoms. They were from 6 mm. 

 upwards in length, and their stomachs contained, as usual 

 in young fishes at these stages, the minute Crustacea called cope- 

 pods. They showed the most interesting changes in the process 

 of transformation to the fully developed fish. At f inch in 

 length (Fig. 146) the development of the permanent fins has made 

 considerable progress. The two dorsals, ventral, and caudal are 

 all marked out and provided with primitive fine fin-rays, but the 

 first dorsal is not separate from the second. The breast-fins are 

 of proportionally enormous size, reaching nearly to the base of 

 the tail, and provided with the permanent fin-rays. It is interest- 



FiG. 145. — Egg of Red Gurnard, alive 

 and magnified. 



o.g. oil-globule ; e. eye ; ///. heart ; an. 

 organ of hearing ; n. notochord, or 

 rudiment of backbone. 



