238 DEEP SEA FISHES. 
wide, nearly vertical. Teeth small, acicular, on jaws, palatines, and vomer, 
Forehead with a ridge at each side. Preopercular and scapular spines. 
A small compressed blade in front of the dorsal fin. An abdominal keel 
composed of the united lower edges of imbricated plates each of which 
covers a lantern. Four gills, fourth small; rakers long, numerous. 
Pseudobranchie, 
Two species known; P. spinosus Giint. secured by the “ Challenger” 
between the Philippines and Borneo, in 250 fathoms, and P. daternatus 
n. sp., taken by the “ Blake” off Barbados, in 221 fathoms. 
Polyipnus laternatus sp. n. 
Polyipnus spinosus G. B., 1896, Oc. Ich., Pl. XXXIX., fig. 148. 
Berar. 95 als Ae 0 ais Vii seb lon Mules Te 
Between P. laternatus and P. spinosus there is not a great deal of differ- 
ence in shape. The outline of the lower surface is but little indented between 
the ventrals and the anal. The length of the head is nearly one third of 
the total length, or a little more than half of the greatest depth; the crown 
has a low sharp ridge at each side. Snout short, blunt. Mouth of 
moderate size, nearly vertical, more than half of its upper border formed 
by the intermaxillaries. Teeth minute, in single series on the jaws, on the 
anterior ends of the palatines, and at each side of the vomer ; the last series 
curving forward toward the palatine. Gill rakers slender, more than half 
as long as the eye, eight plus fourteen on the forward edge of the first 
arch. Pseudobranchiz well developed. Abdominal keel of ten pairs of 
plates. Clavicular and ventral angles short. Scapular spines more than 
one third as long as the eye, directed backward. The blade in front of the 
dorsal is a small, low, compressed ridge which precedes two ridges, with a 
trough between them, that end in a pair of backward upward and laterally 
directed spines immediately in front of the fin. The blade forms a sharp 
angle in front of the trough. Pectoral fins elongate, reaching behind the 
bases of the ventrals. Caudal deep; caudal pedicel deep and strong; 
caudal section not abruptly constricted at the body. 
The lanterns are well developed in both disks and reflectors; they are 
placed as follows: one on the forehead, one in front of and one behind the 
eye, two behind the end of the maxillary—the larger below the orbit, 
six in the branchiostegal series, six on the isthmus, ten along the edge of 
