218 PERCY SLADEN TRUST EXPEDITION. 
advance of the pectorals; 14 or 15 photophores in the lower series from ventrals to 
anterior part of anal and 11 or 12 in the series from middle of anal to caudal. Upper 
series of photophores 36 or 37 in number, running from above the pectoral to above the 
middle of anal. Dorsal 13; origin above the ventrals, equidistant from oeciput and 
base of caudal. Anal 15, its origin some distance behind the end of the dorsal. Greyish ; 
peritoneum blackish. 
Plankton, 77, 750-0 fathoms, near Desroches Atoll. 
A single specimen, 110 mm. in total length. 
Evidently closely allied to the Astronesthes elucens of Brauer, which differs in the 
larger eye (62 in the length of the head in a specimen of 146 mm.) and in having 
only 22 photophores in the upper series, which terminates above the ventral fins. 
I have named this species after Dr. A. Brauer, in recognition of his recent work on 
the deep-sea fishes of the ‘ Valdivia’ expedition. 
2. Chauliodus sloani, Bl. Schn. 
Plankton, N, 600-0 fathoms, north of Peros Atoll. 
3. Helanostomias valdivie, Brauer. 
Plankton, s, 500-750 fathoms, near Farquhar Atoll. 
A specimen of 60 mm. has only 10 teeth in the posterior maxillary series instead of 
28 as in the larger specimen (165 mm.) described by Brauer. 
4. Argyropelecus affinis, Garm. 
Plankton, s, 750-1000 fathoms, near Farquhar Atoll. 
5. Argyropelecus sladeni, sp. nu. 
Depth of body 1% in the length, length of head 3%. Two spines at the angle of the 
preeoperculum, one directed downwards, the other backwards. Dorsal and abdominal 
ridges not serrated; no spines on the caudal peduncle. Post-abdominal photophores in 
3} groups, 4 between ventrals and anal, 6 above the anal fin, 4 on the lower edge of 
caudal peduncle; supra-anal series separated from the praanals by a very short inter- 
space and from the caudals by a distance equal to 2 the length of the supra-anal series. 
Dorsal 9. Anal? Pectoral as long as the head. 
Chagos Archipelago, Salomon, 400 to 500 fathoms. 
A single specimen, 28 mm. in total length. . 
Five species of Argyropelecus may now be regarded as well established, all of which 
are represented in the British Museum Collection; they may be distinguished as 
follows :— 
I, Photophores forming a nearly continuous series . . . . . . IL. affinis, Garm., 1899, 
II. Postabdominal photophores in 8 groups—preanal, supra-anal, and caudal. 
A. Dorsal and abdominal ridges serrated ; a double series of spines 
on the lower surface of caudal peduncle ; preoperculum with 
a single downwardly directed spine . .. . +. + + + « 2 aculeatus, C. & V., 1849, 
