228 STALK-EYED CRUSTACEA. 



Ceratomysis spinosa Fax. 

 Plate L v., Fiij. 2 ; Plate L VI. 



BuU. Mus. Comp. Zool., XXIV. 220, 1S93. 



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 respirator}' 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 pi'oduced 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, Avhich 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 later.al 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 (•3-e-stalks assume the form of two slender styles, the free ends of 



