e 
Maxillary about half of eye. Interorbital comcave, rostral 
keel extending within though much less developed than on snout. 
Opercle without keel, with many fine striae radiating above 
and below. Slight occipital keel medially, notched at each 
segment juncture. Gill-opening small slit, neerly or quite 
horizontal, 2 to 4 times its own length from pectoral origin. 
Rines firm, no spines on keel; each ring with many fine trans- 
verse striae. The brrood pouch of the male extends over 12 to 
15 rings. Dorsal origin begins usaeally well forward on second 
ring, before vent, and extends on five body rings. Anal nearly 
as long as eye, inserted on ring just behind vent. Caudal elon- 
gate. Color dull brown, faded in spirits, some dark specks and 
streaks on sides and above. 
Four specimens from Rio Janeiro, 79 to 115 mm. 
Compared with ten fine examples of S. pelagicus Osbeck, 
in the Academy collections from the Mediterranean, we find 
the following differences:- In S, roussean the head is much 
smaller, body depth ereater, dorsal rays fewer, body rings 
fewer, eye larger, dorsal beginning well before vent or at 
least on 2 body-rings, and male brood pouch on fewer rings or 
at least area long as rest of tail. Jordan and Ewermann give 
the distinctions as fewer dorsal rays, or 29 to 32 for 5S. pel- 
> ae . 
agicus, “Whereas gil our examples show the lowest number 356. 
Moreover the head has a slightly stronger keel in ©. rousseau,. 
Our examples all show several more rings. The Academy spec- 
imens of S. pelagicus have: Head 2 to 2 7/8 to vent; depth 
4+ in head; D. 36 to 39; rings 19 to 22 - 35 to 43; 
to 2 in head; eye 3 to 6 2/3 in snout; pectoral 22 
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