REPRODUCTION AND SEX 505 



pigmy male (in one case two of them) very intimately attached to 

 her body and dependent on her for sustenance. In two of these 

 strange fishes the blood-vessels of the snout end of the little male 

 were in actual continuity with those of a papilla-like process of the 

 female's skin; and this is the only way in which the male can get 

 any nutriment. The pigmy is an ecto-parasite ; and the continuance 

 of the weird association must be due to the fact that it secures the 

 fertilisation of the eggs when these are shed into the sea. The need 

 for the extraordinary inter-relation, which is unique among back- 

 boned animals, becomes more intelligible when we notice where 

 these deep-water Anglers live. Unlike their relative, the Common 

 Angler or Fishing-frog (Lophins), which lives as an adult in rela- 

 tively shallow inshore waters, the Ceratioid Anglers with the para- 

 sitic males live^in the dark middle depths between 250 and 500 



Fig. 75. 



Angler-fish {Photocorynus spiniceps), showing Male Parasitism. After Tate 

 Regan. A, the female (F) with the pigmy male (M) attached to the front 

 of her head. B, the male (M) enlarged, showing his close attachment to 

 the front of the head of the female (F) . 



fathoms. They are for practical purposes beyond the light limit, 

 and yet they are not on the deep-sea floor where some other kinds 

 of Angler-fishes have their home. They seem to capture other fishes 

 that are attracted to their luminescent lure, but they do not find 

 life easy. They move slowly in the dark water, and they are few 

 and far between. The fertilisation of the eggs would be precarious, 

 were there not some special adaptation, and thus has arisen the 

 lasting attachment of the pigmy males to the females. 



While the state of affairs disclosed by Mr. Tate Regan is unique 

 among Vertebrates, it has some striking parallels among backbone- 

 less animals. Long ago, when he was monographing barnacles, 

 Darwin discovered that some of them bore dwarf and degenerate 

 males, which he called "complemental". As they may occur on 



