EEPORT ON THE DEEP-SEA FISHES. 241 



Halosaurus rostratus (PI. LIX. fig. D). 



Halosaurus rostratus, Giintli., Ann. and Mag. Nat. Hist., 1878, vol. ii. p. 252. 

 B. 9. D. 10. V. 9, 10. L. transv. 13 | 6. 



The length of the head much exceeds the height of the body. The snout very- 

 much produced, spatulate, its prseoral portion being more than one-half of its length. 

 Eye of moderate size, its length being one-third of the postocular portion of the head, 

 and considerably less than the width of the interorbital space. Maxillary scarcely 

 reaching the front margin of the eye. The length of the head is a little more than its 

 distance from the root of the ventral, which is nearly entirely situated before the dorsal. 

 Nearly all the scales are lost, but some of the lateral line remain ; they are much larger 

 than the other scales ; and on the tail, where the lateral line approaches the lower 

 profile, these larger scales fill up all the space between the lateral line and the anal fin. 



Distance of tlie snout from the mouth, , 



Distance of the snout from the eye. 



Distance of the snout from the root of the pectoral, 



Distance of the snout from the root of the ventral. 



Distance of the snout from the origin of the dorsal, 



Distance of the snout from the vent. 



Total length, . . . , , 



Habitat. — Mid-Atlantic, Station 63 ; depth, 2750 fathoms. One specimen, 

 20 inches long. 



Bones of the head very thin ; operculum smooth, covered with a very fine membrane. 

 The lower part of the side of the head is occupied from the snout to the gill-opening 

 by two exceedingly wide muciferous channels, of which one takes its origin on the 

 prseorbital, the other on the mandible, and which open behind at the gill-opening by a 

 common and very wide aperture. Branchial apparatus as in the other species. 



The dentition is very similar to that of Halosaurtts macrochir, but the palatine 

 patches are crescent-shaped and rather widely separated from the pterygoid band. 



The scales of the lateral line are about three times the size of the others, and about 

 twenty-four in number between the gill-opening and the vent. Each bears a luminous 

 organ, vertically elongated and rhombic, but not extending to the upper or lower 

 margins of the scale. Light coloured, the lower part of the head and the gill-cover 

 black ; abdominal region blackish. 



Halosaurus affinis (PI. LIX. fig. B). 



Halosaurus afflnis, Giinth., Ann. and Mag. Nat. Hist., 1877, vol. xx. p. 4-14. 

 Snout much produced, but less so than in Halosaurus rostratus ; its pr^oral portion 

 being scarcely one-half of its length. Eye of moderate size, one-third of the postocular 



(ZOOL. CHALL. EXP. — PART LVII. — 1887.) L^ 31 



10 



