346 MARKETABLE BRITISH MARINE FISHES 



condition by Professor Mcintosh, at St. Andrews, in January, 

 1886. These were in an advanced stage of development, and 

 many of the larva; hatched out during the four or five days after 

 the}' were received. 



The length of the hatched larva (Fig. 153) is ii or 12 mm. 

 or nearly ^ inch. The body is transparent and slender, and 

 surrounded in the middle line behind by a narrow fin-membrane. 

 The yolk-sac is very large in proportion, and is longer from its 

 attachment downwards than in the direction of the length of 

 the fish ; it is attached therefore by a rather narrow base. In 

 the middle of its front surface is a large single oil globule. The 

 yolk is straw-coloured and somewhat transparent, and on its 

 surface is a network of blood-vessels. There is some pigment 

 in the eyes and on the back of the head, but scarcely any else- 

 where. The mouth is open, but small. Some of these larvae, 



Fig. 152. — Eggs of the Cat-fish, natural size ; after Mcintosh. 



hatched at the end of January, lived in the St. Andrews 

 laboratory until May 14th, by which time the yolk was all 

 absorbed, the jaws and teeth well developed, and delicate fin- 

 rays had appeared in the longitudinal fins and tail-fin (Fig. 154). 

 The eye was relatively much larger than in the adult. The 

 shape was that of the full-grown fish, and the colour was a dark 

 smoky-brown except on the belly. The fish had not grown 

 greatly in length : the exact measurement is not given, but from 

 the figure it appears to have been about f inch. It is interesting 

 to note that the absorption of the yolk which in the case of a 

 larva like that of the plaice, occupies about a week, lasted in the 

 cat-fish three months and a half, and also that while in the plaice 

 the larva has to feed itself for about two months before it has 

 completed its development and reached the perfect condition, 

 in the cat-fish the development of the skeleton and all the 



