154 THE ANGLER FAMILY. 



There seems to be a great deal of uncertainty concerning 

 the stages between the post-larval fish already described and 

 figured (fig. 6) and the stage at which the adult characters are 

 assumed. 



Both Day and Giinther in their treatises give figures of a 

 young angler-fish which agree the one with the other. The 

 former author remarks, ' in the young the head is broader 

 than long, but less depressed than in the adult. The de- 

 pression increases with age while the spines of the first dorsal 

 fin have lateral soft-branched enlargements along their anterior 

 and posterior edges.' Giinther also observes that the ' first 

 dorsal spine bears a ciliated bifid appendage and the next four 

 rays are of a racemose feathered type. There are huge ventral s 

 with four free rays, extending to behind the tail.' 



This description to some extent agrees with that given by 

 Diiben and Koren of a young angler from Norway which had 

 the first dorsal spine terminating in a transverse cylindrical knob, 

 provided with cilia, and being scarcely above half the length 

 of the second spine. This young form so differed from the 

 adult angler that the above-mentioned observers supposed it to 

 be a separate but allied species and even gave it the name of 

 Lophius eurypterus. 



The gradual broadening and flattening of the head spoken 

 of by Day is a process we should expect to occur at quite a 

 late stage of development as being a feature in which the 

 angler differs from the general Teleostean type, and which has 

 been acquired comparatively recently in correlation to its 

 environment ; the peculiar feathered tentacles and the enormous 

 ventral fins, on the other hand, must be post-larval characters 

 of a transitory nature as they are not found in fig. 6 and are 

 also absent in the adult. The long ventrals are present at the 

 age of 15 days. One cannot, however, pronounce a definite 

 opinion upon this point until more certain knowledge is obtained. 



The rarity of the post-larval and young forms when 

 compared with the common occurrence of the adults only tends 

 to the supposition that there must be some element in the 

 environment or habit of these stages of which we are at present 

 in ignorance. 



