250 THE VOYAGE OF H.M.S. CHALLENGER. 



Total length, ....... 290 mm. 



Length of the head, ...... 45 „ 



Depth of the body, . . . . . . 30 „ 



Length of the tail, . . . . . . 182 ,, 



Habitat. — South -Western Coast of South America, Station 310 ; depth, 400 

 fathoms. One specimen, 11^ inches long. 

 Mediterranean. 



As Kisso correctly states, the number of maxillary (" mandibule," Risso) teeth is 

 from twenty to twenty-two on each side, that of the mandible (" machoire," Risso) 

 twenty, and that of the palate twenty -four. The posterior part of the paired fins and 

 the lower of the anal are black. Cavity of the mouth and gills black. Structure of the 

 air-bladder as in Notacanthus sexspinis. 



Filippi and Verany ' have shown that Risso, in figuring and describing his 

 Notacanthus honapartii, has confounded two species. The name ought to be retained 

 for the specimen described, without reference to the figure which itself is evidently very 

 faulty. 



B. Polyacanthonotus. 



Notacanthus rissoanus (PI. LXI. fig. B). 



Notacanthus rissoanus, FOippi and Verany, Mem. Ace. Sci. Torino, xviii. p. 190. 

 B. 9. D. 34. A. 54 I ^ (79). C. 6. P. 11. V. 1 | 9. 



The greatest depth of the body is opposite the vent, and one-fifth of the distance 

 of the vent from the end of the snout ; the length of the narrow, long, compressed 

 head is one-third of the same length. The snout is compressed, pointed, much pi'O- 

 duCed beyond the narrow mouth, the cleft of which laterally extends to below the 

 posterior nostril. Each jaw is armed with a series of fixed minute teeth ; a similar 

 palatine series within the intermaxillary series ; the mandibulary series fits between 

 the upper two rows. The eye is close to the upper profile, and distant two diameters 

 from the end of the snout, and four from the extremity of the opercle ; its diameter 

 exceeds the width of the interorbital space. The gill-opening is wide ; the gill-mem- 

 branes are supported by very slender branchiostegals, confluent in front, and not 

 attached to the isthmus. 



The whole body and head are covered by minute, smooth, imbricate, and adherent 

 scales. 



All the dorsal spines are short, distant from one another, the first being above the 



' Mem. Ace. Sc. Torin., xviii., 1859, p. 188. 



