152 THE ANGLER FAMILY. 



The serous space above the head becomes distended. The 

 ventral fins are also long and filamentous with a second short 

 ray appearing at the base of the first. Plate VI, fig. 5, shows 

 these features in the post-larval form 15 days after hatching, 

 and in views from above it is apparent that the flattening of 

 the head and trunk, which is so characteristic of the adult, has 

 already taken place to some extent. By this flattening the 

 eyes come to lie completely upon the dorsal surface, and look 

 upwards. At this point one reaches the stage where the post- 

 larval phase of development succeeds the larval, and the young 

 fish no longer has yolk from which to obtain its supplies of 

 nutriment. It is difficult in tanks to provide the suitable food 

 and surroundings, and hence our knowledge of the further stages 

 has to be gleaned piecemeal by the tow-net. 



Here we encounter a peculiar developmental feature of the 

 angler-fish, for during all the continued trawlings of the East 

 coast waters which have been conducted for the last few 

 years, one and only one post-larval stage of the angler has 

 been forthcoming. This curious little fish has been described 

 in detail elsewhere 1 and is figured in Plate VI, fig. 6. As 

 will be seen it differs in several important respects from the 

 15-days-old larva. It was caught in the mid- water net, 15 miles 

 off the Isle of May, at a depth of 25 fathoms. It is somewhat 

 over | inch (7 mm.). The large flattened head and tapering 

 little tail give it a tadpole-like aspect. The gape is large and 

 the snout very blunt with a median notch. The eyes are large 

 and round and look directly upwards. Part of the continuous 

 embryonic median fin is still present, and the paired pectoral 

 fins are enormously developed, stretching backwards and 

 outwards as two fan-like processes ; the ventrals on the other 

 hand are small, and although broken, appear to have been 

 poorly developed, a feature in marked contrast to the condition 

 of the pectoral and ventral fins of the 15-day larva, where their 

 relative sizes and importance are exactly reversed. The gill-slits 

 are still large and long and differ greatly from the little con- 

 tracted pore-like apertures of the adult. 



From these observations it will be seen that there are 

 1 Trans. R. S. E. vol. 35, pt. in. p. 869. 



