ANGLER FISHES GILL. 



587 



THE ACERATIIDS. 



Another family related to the Ceratiids is that of the Aceratiids, 

 which contrasts remarkably Avith the Gigantactinids by the complete 

 loss of the illicium; the family name refers to this characteristic. 

 The body is more or less oblong or even elongate and subcylindrical, 

 and the cej^halic region smaller than in the Ceratiids. The mouth 

 cleft is not much, if any, above the horizontal line. The pectorals 

 are like those of the Ceratiids, but the dorsal and anal are much 



Pig. 26.— Type of the family Aceratiids (Accratias macrorhinus). After Brauer. 



reduced in size and far back ; the ventrals absent. The illicium is 

 entirely suppressed, but the interspinal bone appears to be developed, 

 though mostly concealed beneath the skin.'* Instead of the lantern- 

 like or phosphorescent bulb of the illicium manifest in the Ceratiids, 

 the nasal capsules of the Aceratiids are peculiarly developed and 

 may perhaps exhibit phosphorescent emanations. 



No species of this group were known till the present decade and 

 the cruise of the deep-sea expedition of the German steamer Valdivia. 



Figs. 27, 28. — Side and front views of the head of Aceratias indicus. After Brauer. 



On overhauling the fishes of the expedition sj^ecimens were found by 

 Dr. A. Brauer, noticed in 1902, and later (1908) referred to a "new 

 family." 



Three forms of the family have been described by Doctor Brauer, 

 all obtained from depths of 1,000 fathoms or more — one in the Atlan- 

 tic Ocean and two in the Indian Ocean. All the specimens were 

 young, being less than an inch long. 



" Doctor Brauer has not described an interspinal bone, but his figure (PI. XVI, 

 figs. 8 and 9) seem to represent one; so, at least, I am tempted to interpret the 

 illustrations. 



