602 
BULLETIN OF TTIE UNITED STATES FISH COMMISSION. 
nating in a spine directed downward and backward, with a short spine at its base behind; in front of 
the spine, the margin of the plate is minutely serrulate; the plate before the dorsal fin is formed by 
fusion of the 7 protruding interspinals, which are regularly graduated in length, the last two of equal 
length and closely apposed, the others evenly spaced; no trace of an adipose dorsal fin; anterior anal 
ray under last ray of dorsal; distance from last anal ray to first rudimentary caudal ray slightly 
exceeding length of anal base; the anal consists of 6 closely-set anterior rays and 5 more widely-spaced 
shorter posterior rays; pectorals long, reaching base of ventrals. The ventrals are injured, but one fin 
being present, and in such condition that it can not be described. Caudal gently forked. 
The genus Argyropelecus is supposed to be scaleless, but the species here described is covered with 
extremely thin, high and narrow scales, wholly similar to those of Polyipnus. But few of these scales 
remain, in scattered patches, in the type. Where they have been lost, no scale pouches are evident. 
Photophores arranged as in other species of the genus: A group of 4 at the base of the lower caudal 
lobe, a group of 6 above the fifth to ninth anal rays, the distance separating these groups nearly twice 
the length of the anal series; a series of 4 between ventrals and anal, and a series of 12 along the 
ventral margin, between pectorals and ventrals; above the posterior portion of the ventral series is a 
second horizontal row of 6 spots, on a level with the base of the pectorals, and in advance of these are 
2 spots at a higher level, the posterior higher than the anterior; a small spot behind lower margin of 
orbit, one behind and one before preopercular angle, a series of 6 on each side of breast in front of 
pectoral fins, and a series of 6, one at the base of each branchiostegal membrane; each spot or group 
of spots has a deeply pigmented area above it. 
Color: Greater part of head and trunk blackish, middle of trunk with silvery sheen; snout and 
mandible largely translucent; caudal peduncle whitish, with a series of small black spots along anterior 
half of middle line, a dark blotch on middle line at base of caudal fin, and a black area in connection 
with each group of photophores; front of mouth whitish, back of mouth and gill cavity jet-black. 
The stomach was everted in the type, indicating that it came from a considerable depth. But one 
specimen was secured. 
Family CHAULIODONTID^E. 
Cyclothone rhodadenia, new species. Plate 71, fig. 1. 
Type, a female, 192 mm. long (excluding caudal), from station 4108, Kaiwi Channel, depth 411 to 
442 fathoms; type, No. 51584, U. S. Nat. Mus. 
Very dosely allied to C. elongata (Gunther) (Deep-Sea Fishes, Challenger, p. 173, pi. 45, fig. B), 
from the Indian Ocean south of New Guinea, differing in the more numerous branchiostegal rays, the 
more posteriorly inserted ventrals, the more anteriorly placed adipose dorsal, the development of the 
glandular areas on caudal peduncle, and minor details in number and arrangement of lateral 
photophores. 
D. 14; A. 30 or 31 ; P. 11 to 13; V. 8. The type and the single cotype measure respectively 192 mm. 
and 76 mm. in total length, exclusive of caudal fin. Below is a table of comparative measurements, 
expressed in hundredths of this length. 
