270 DEEP SEA FISHES. 



Dactylostomias, in which the head resembles that of Astronesthes and the 

 body that of Stoinias. In this new genus the pectoral is more degraded than 

 those of Opostomias or of Echiostoma since the fin properly so called has dis- 

 appeared and left only the single long filamentary ray. The nearest ally of 

 Dactylostomias is probably Grammatostomias, from the northwestern Atlan- 

 tic, in which genus however the pectoral fin has been retained without the 

 detached or isolated ray. 



CHAULIODIDyE. 



Chaidiodid(B Bonap., 1845 ; Chauliodontidw Bonap., 184G. 



The barbel possessed by the species of the genus Chauliodus has appar- 

 ently been entirely overlooked by all authors who have dealt with the 

 members of this family. The organ is small but distinct on the compara- 

 tively well known species ChauUodiis SJoaui, and is rather more distinct on 

 other forms (see Plate K, figs. 3 and 2a, on which it is outlined from below as 

 seen on C. harhatus and C. Sloani). It is a fleshy, pointed, worm-like append- 

 age situated on the chin between the angles on the lower edge of the lower 

 jaws. It is translucent- and contains a series of isolated black bodies, each of 

 which bears a reflecting facet on the lower (hinder) side. A larger luminous 

 organ rests below the base, and more or less backward from this there are two 

 others. From the muscles used in the control of its movements, its function 

 is probably one of considerable importance. In classification the presence of 

 the barbel necessitates the removal of the genus farther from Gonostoma and 

 other Sternoptychoids, and places it nearer to the Stoniiatoids. It empha- 

 sizes the necessity of adopting Bonaparte's family, the ChauliodidiB. On all 

 of the five or six known species an adipose dorsal fin is present. The vari- 

 ous published figures r^jpresenting Chauliodus without this fin are incorrect 

 (for instances see Bl. Schn., 1801, pi. 85, — Shaw, 1804, V, pi. Ill,— 

 Swainson, 1838, I, fig. 65, — Valenciennes, 1850, pi. 97, fig. 3). On the 

 other hand those illustrations which represent species of Chauliodus with a 

 second dorsal containing rays like those of the anal fin are equally erroneous 

 (see Risso, 1826, III., fig. 37, — Bonaparte, 1841, Fauna Ital., — Giinther, 

 1880, Introduction, fig. 285). 



These fishes no doubt frequent considerable depths, but whether they 

 habitually stay close to tlie bottom is still an open question. The greatest 

 depths were assigned them by the " Cliallenger," northeast of the Bermudas, 



