172 
BULLETIN OP THE UNITED STATES PISH COMMISSION. 
Thynnichthys Giglioli, Catal. Pesci Italiana, ‘25, 1880 ( thunnina ); not Thynnichttiy's Bleeker, a genus of Cyprinidse. 
Euthynnus Liitkeu MS. (in Jit. Feb.. 1881). Jordan & Gilbert, Synopsis, 429, 1883 (thunnina). 
a. Lateral line with a decided curve below second dorsal: 4 lengthwise stripes on sides of body below 
lateral line. :..pclaniis , p. 172 
a a. Lateral line without distinct curve: no stripes below lateral line. alletterata, p. 173 
125. Gymnosarda pelamis (Linnaeus). “Aku;” a Ocean Bonito. Fig. 64. 
Head 3.5 in length; depth 4; D. xv-12-vm; A. ii, 12-vii. 
Body oblong, robust; lateral line making a decided curve immediately beneath the second dorsal; 
corselet strongly developed, covering the entire space between the diagonals connecting the posterior 
extremity of the spinous dorsal and the base of the pectorals; posterior margin of preopercle about 1.5 
in inferior margin; pectorals reach vertical from tenth dorsal spine. 
Back bluish; belly silvery; 4 brownish stripes on each side of belly, parallel wdth the lower curve 
of body; no spots below' pectorals. 
Warm seas; pelagic; not very common, north to Cape Cod and Bermudas on the Atlantic coast of 
America; once recorded from California. 
A specimen (No. 04439) 32 inches long, from Honolulu, is described as follows: 
Head 3.3 in length; depth4.4; eye 7.75 in head; snout 3.2; maxillary 2.7; mandible 2.3; gape,2.7; 
interorbital 3.6; D. xvi-12+8; A. ii, 12+7. 
Body rather short, stout, not compressed; head and caudal peduncle uniformly pointed; head 
rather large, long, conic; snout small, sharply conic; mouth moderate, the jaws subequal; maxillary 
reaching middle of pupil, slipping under preorbital, width at tip 1.7 in eye, lower edge convex, fitting 
into a concavity in mandible; teeth small in both jaw's, none on vomer or palatine; short, sharp teeth 
on base of tongue; interorbital space broadly convex; eye rather small in anterior half of head; opercle 
and preopercle with fine but soft serrations; caudal peduncle short, depressed, and strongly keeled; 
origin of spinous dorsal slightly behind base of pectoral, the anterior spines produced, 2 in head, the 
fin folding in a groove; distance between dorsal fins very short, not exceeding diameter of eye; anterior 
dorsal ray produced, 3.1 in head; anal similar to soft dorsal, its origin under last dorsal ray, its anterior 
rays produced, equaling those of dorsal; caudal extremely broadly forked, the lobes small, scarcely 
exceeding snout and eye in length; pectoral moderately long, pointed, 1.9 in head; ventrals shorter, 
2.75 in head; corselet well developed; a large naked area on side anterior to line connecting origin of 
soft dorsal to tip of pectoral; lateral line with an irregular arch above the pectoral, thence descending 
in an irregular wavy line to keel of caudal peduncle. 
U In ancient tradition the ‘■Aku” and th e“Opelu" (mackerel) accompanied Pili on his voyage to Hawaii. “ Aku ” ' 
helped to paddle the canoe, and “Opelu " calmed the winds when too strong. 
