or bulges or is studded with bony plates. While usually blackish or brownish, the skin is trans- 

 parent in Halopliryne, revealing the intestines and muscles, which are enclosed in a gelatinous 

 mass. The teeth are variable in form, being very large in Melanocetus johnsoni, one of the 



A large female ceratioid angler-fish (Ceratias holboelli), with two dwarf males attached to the abdomen. 



earliest known ceratioids. The length ranges from an inch or so to about two feet in Hiinan- 

 tolophus grocnlandicus and even to more than a yard in Ceratias holboelli. 



For biologists, the most remarkable feature of this family is an extreme difference between 

 the forms of the sexes, the difference in size being exaggerated to a degreee unknown in other 

 vertebrates. The males are veritable dwarfs. The visceral organs have disappeared and the 

 body cavity merely contains a large testis. These small creatures fasten themselves by their 

 jaws to the skin of the large females which grows around this contact to make a lasting fusion. 

 Nevertheless, respiration and blood circulation are kept as distinct activities. This fixing 

 process takes place during the larval development of the dwarf males and it is only afterwards 

 that the genitalia develop. Polyandry is the rule, each female carrying several parasitic males 

 attached to her underparts. Among the groups of animals it is not until we come to certain 

 Crustacea that a comparable " dwarfism " is encountered. A cogent explanation of this 

 paradoxical degeneration has yet to be found. 



At far greater depths along the red clay of the deep-sea floor; between depths of 2,000 and 

 3,000 fathoms, live the highest of the invertebrates, theelasipod holothurians — flattened like a 



At depths beyond 2,500 fathoms on the deep-sea floor. Brotulid fishes between two elasipod sea-cucumbers. 

 In the middle Barathronus parpariti. On the left two Leucochlamys cryptophthalmus. 



sole and set with stifT appendages. Slithering among them are degenerate looking creatures. 

 They are pallid, blind and eel-like and they are brotulids, the last representatives of the versa- 

 tile class of fishes in the deepest reaches of the abyss. 



181 



