644 TELEOSTEI chap. 



1 2 feet, it must be immune to their influence : a remarkable 

 condition, considerins that small fish have often been seen in 

 their stomachs and entangled in their tentacles." This observer 

 adds : " It is probable that, in addition to protection, the fish 

 derives its food from association with the Physalia, much as does 

 the Eemora in accompanying a shark. The Physalia doubtless 

 paralyses many more animals than it can consume — the residue 

 falling to the lot of the fishes, which may be present to the 

 number of ten." 



Fam. 10. Icosteidae, — The so-called "Eag-Fishes," in which the 

 skeleton is quite soft and cartilaginous, are aberrant deep-sea 

 forms evidently related to the Stromateidae ; they lack the 

 oesophageal teeth and the processes of the last gill-arch, but 

 Icosteus at least has the gill-raker-like knobs below the pseudo- 

 branchiae. The pelvis is widely separated from the clavicles. 

 Spines are absent in the fins, and the body is naked or covered 

 with small cycloid scales. Vertebrae in large number (up to 70). 



Icosteus, Icichthys, and Acrotus, each with a single species, 

 from the Pacific coast of North America. 



Fia. 393. — Icosteus enigmaticun, x J. (After Goode and Bean. ) 



Fam. 11. Ophiocephalidae. — Maxillary excluded from the 

 border of the upper jaw. Head and body covered with cycloid 

 scales. Anterior ribs sessile, the remainder inserted on the para- 

 pophyses. Pectoral fin low down ; ventral fin, if present, near 

 the pectoral, with 6 soft rays ; pelvic bones connected with the 

 clavicular symphysis by ligament. Dorsal and anal fins long, 

 without spines. Air-bladder present, much elongate. 



These Fishes are provided with an accessory superbranchial 

 cavity, and are able to breathe atmospheric air. All are inhabi- 



