THYSANOPODA CRISTATA. 209 
long. 115° 20’ E. Probably all the specimens in the Copenhagen Museum were 
taken at the surface of the sea during night. 
3. Thysanopoda cristata G. O. Sars. 
Plate 3, figs. 4a-4c; Plate 4, figs. la—th. 
1883. Thysanopoda cristata G. O. Sars, Forh. Vid. Selsk. Christiania for 1883, no. 7, p. 22. 
1885. Thysanopoda cristata, G. O. Sars, Challenger Rept., 13, p. 104, pl. 18, figs. 15-20. 
1893. Thysanopoda biproducta ORTMANN, Ergebn. der Plankton-Exped., 2, G. b. p. 8, taf. I, fig. 1. 
Sta. 4699. Dec. 25, 1904. Lat. 21°39.5’S., long. 104° 29.8’ W. 300 fms. to surface. 1 young speci- 
men. 
Sta. 4728. Jan. 19, 1905. Lat. 13° 47.5’S., long. 114° 21.6’ W. 300fms. tosurface. 1 adult male. 
Sta. 4736. Jan. 23, 1905. Lat. 19° 0.4’ S., long. 125° 5.4’ W. 300 fms. to surface. 1 immature 
specimen. 
» Description — The frontal plate (Plate 3, fig. 4b) long, only a little broader 
than long with the lateral margins considerably concave, strongly tapering 
forwards and narrow in front, where it terminates in a moderately short, slender 
rostrum which at its base is distinctly narrower than the end of the plate; in 
the adult specimen (and in Sars’s type) the rostrum seems to be articulated to 
the end of the plate, but whether this is the normal state or is due to injury 
I cannot decide. In the two much smaller specimens the rostrum is broader 
at the base and not well-marked off. At the anterior end of the frontal plate 
a very conspicuous, somewhat high, sharp dorsal keel is suddenly raised (Plate 3, 
figs. 4a and 4c), the front end of which is even emarginate and terminates above 
in a point; the keel goes backwards to near the middle of the carapace, and 
about at the middle of its length, where the dorsal organ is found, it is rather 
suddenly somewhat higher, while it is rounded downwards towards its posterior 
end; in the smallest specimen the keel has no angle or incision at its front end, 
and its anterior half decreases in height towards the rostrum where it disappears. 
The carapace has no cervical suture, but two oblique, moderately short impres- 
sions on each side at a distance from the front lateral margin of about one third 
of the length of the carapace; the upper of these impressions is nearly horizontal, 
the lower very oblique and below limited by a low narrow ridge. The lateral 
part of the front margin of the carapace below the eye is produced in a triangular, 
acute, somewhat small plate; at a considerable distance from the lower margin 
a deep furrow is seen, beginning above the insertion of the maxilla and reaching 
to near the hind margin of the carapace, where it bends upwards and terminates 
at the middle of the side. A small tooth (omitted in fig. 4a by the engraver) 
is found above the lateral margin —in the small specimen on the margin — of 
the carapace somewhat before its posterior end; the tooth is acute, directed 
outwards, forwards, and downwards. 
