964 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
SYSTEMATIC ACCOUNT OF THE SPECIES. 
Order EUPHAUSIACEA Boas. 
Family EUPHAUSIIDA Dana. 
Genus THYSANOPODA Milne-Edwards. 
1. Thysanopoda obtusifrons G. O. Sars. 
Thysanopoda obtusifrons G. 0. Sars, Rep. Voy. Challenger, 13, 102, pi. 18, figs. 1-14, 1885; Alcock & 
Anderson, Journ. Asiat. Soc. Bengal, 1894, 63, 3. 
A careful comparison of the present material with Sars’s description has led to the conviction that 
these specimens agree better with this species than those collected by the Plankton Expedition in the 
Atlantic, and described by the present writer under this name.® ,The only difference from Sars’s 
account I am able to discover is that the preanal spine in most of our specimens is present and simple; 
it was seen in 14 of them, while 3 did not show it (the remaining 1 was dissected before it was 
examined in this respect). Sars calls this spine “obsolete,” but we must bear in mind that he had 
only 3 individuals at his disposal. 
Further, the lobe of the first joint of the antennula is different in shape from that given in Sars’s 
figure (fig. 2 on pi. 18); its inner portion, projecting over the base of the second joint, is drawn as 
square (with rounded angles), while in our specimens (I have made, however, only one slide) it is 
rather triangular, the inner angle being produced. 
For the rest, our specimens agree completely with T. obtusifrons, and we are to mention especially 
that there is no lateral denticle on the carapace, and that the serrate keels of the telson correspond 
closely to Sars’s description and figure (fig. 3, pi. 18). In these respects and in size (our largest is 
19 mm. long; Sars gives 23 mm. ) they differ from the specimens taken by the Plankton Expedition 
and specimens recorded under this name from the Mediterranean . !> This Atlantic species has recently 
been called T. vulgaris by Hansen. c 
Stations: 3806, 50 fathoms, 23° 25 / 36" N., 152° 24 / 30" W., Erben Bank to Kaiwi Channel, 5 
specimens; 3888, 50 fathoms, 22° 10 r N., 155° 35' 45" W., northeast of Kaiwi Channel, 13 specimens. 
Distribution. — “Pacific” and “South Pacific” are the localities given for the specimens collected 
by the Challenger. Alcock and Anderson mention it from the Laccadive Sea, Indian Ocean, 1,250 
fathoms. 
2. Thysanopoda agassizi Ortmann. 
Thysanopoda agassizi Ortmann, Bull. Mus. Harvard, 14, 1894, 99. 
The individual at hand is much larger than the specimens previously recorded. The largest from 
the Panama region measures 19 mm., while the present one is 32 mm.; but it agrees completely with 
the description, except that the preanal spine is well developed and has two points, one shorter than 
the other. 
Color in life, according to label: “Light vermilion, darkest on thoracic feet.” 
Station: 3804, 50 fathoms, 24° 58 / 42" N., 149° IV W., between Erben Bank and Kaiwi Channel, 
1 specimen. 
Distribution. — Gulf of Panama, 200 fathoms, and between Galapagos and Acapulco, 0-200 fathoms 
(Ortmann). 
Genus EUPHAUSIA Dana. 
3. Euphausia bidentata (G. O. Sars). 
Euphausia pellucida G. O. Sars, Rep. Voy. Challenger, 13, 1885, 75, pi. 11 and 12; Ortmann, 
Decap. & Schizop. Plankton Exped., 11, 1893; Ortmann, Bull. Mus. Harvard, 25, 1894, 101. 
Caullery, Ann. Univ. Lyon, fasc. 2, 1896, 367. Holt & Tattersall, Rept. Fish. Ireland, 2 app., 
4, 1905, 101 and 133. 
a Ortmann, Decapoden und Sehizopoden Plankton Exped., 1893, p. 10. 
i>Salv. lo Bianco, Pclagische Tiefseefischerei der “ Maja,” p. 35, pi. 14, fig. 48, 1904. Capri, Naples, about 1,000 m. 
c Hansen, Bull. Mus. Oceanogr. Monaco, No. 30, 1905, p. 15. 
