228 STALK-EYED CRUSTACEA. 
Ceratomysis spinosa Fax. 
Plate LV., Fig. 2; Plate LVI. 
Bull. Mus. Comp. Zodl., XXIV. 220, 1893. 
The cephalo-thorax is somewhat longer than the abdomen minus the 
telson ; the two posterior thoracic segments are completely exposed behind 
the short carapace, which is one half as broad at the anterior end as it is 
long. The anterior margin of the carapace is straight; not rostrate, but 
produced at each lateral angle to a long horn directed obliquely forward ; 
the cervical groove is pronounced, as is also the tongue-shaped dorsal area 
behind it; in front of the cervical groove are three long erect spines in the 
median line, the foremost of which is on the frontal margin; there is, besides, 
a spine on each side of the carapace in a transverse line with the middle one 
of the median three; behind the cervical groove there is one spine in the 
median line near the posterior margin of the carapace, two on each side of 
the tongue-shaped dorsal area, and a long row of six on each side, in line 
with the lateral spines of the gastric area; a rounded notch in the anterior 
part of the lateral border of the carapace, in which the epipod of the second 
maxilla plays, serves as an outlet for the respiratory currents; behind this, 
the lateral margin is somewhat concave and terminates posteriorly in a sharp 
tooth; the hind border of the carapace is sinuous, but not produced into 
pronounced lateral wings. The last two thoracic segments, — those that are 
not covered by the carapace, — are each armed with a median dorsal spine ; 
their lateral borders are drawn out into a long spine; the ultimate segment 
has in addition a spine on each side between the median and marginal spines. 
The row of median dorsal spines is continued along the abdomen, there being 
one spine on each segment except the first, which bears two, — the posterior 
one deeply bifid; the hindmost of the median abdominal spines is situate on 
the base of the telson, and is smaller than those in front of it; there are, 
moreover, two lateral longitudinal rows of spines on each side of the abdo- 
men, one on the lower lateral margin, and one between this and the median 
dorsal row. The sixth abdominal segment is but little longer than the fifth. 
The telson is very narrow and long, nearly equalling, indeed, the length of 
the remaining portion of the abdomen; it narrows a little toward the hinder 
end, which is truncate ; the margins are setose and slightly scalloped toward 
the posterior end. 
The eye-stalks assume the form of two slender styles, the free ends of 
