ECHINOCAKIS. PPP. 11 



and occupying about a foiirtli of each valve. This area is 

 ornamented in eacli valve with a prominent rounded tuber- 

 cle at its posterior dorsal apex ; and a large rounded eleva- 

 tion occupying the whole anterior end of the valve, making 

 in all four prominent elevations on the cephalic area. The 

 optic node is situated on the lower side of the largest tuber- 

 cle and adjacent to the limiting furrow. 



The thoracic portion of the valve is ornamented with an 

 elongate tubercle near the middle of the anterior portion, 

 produced into a nodose ridge following the contour of the 

 lower margin and djing out before reaching the posterior 

 end. A similar tubercle, but situated transversely, is found 

 in the upper dorsal portion, and is continued in a nodose 

 ridge adjacent to the dorsal line, and along the posterior 

 margin of the valve. In the center of the area partially 

 enclosed by these two ridges is a less prominent longitudinal 

 row of minute nodes forming a third carina. 



The valves are also ornamented with minute irregular 

 tubercles on the summits of all the elevated portions of the 

 valves, a single row appearing along the three ridges and 

 around the extreme margin of the posterior portion. 



Abdomen composed of six naked segments, which be- 

 come more elongate towards the telson. Somites cylindri- 

 cal, marked by a thickened rim on the anterior end ; orna- 

 mented with four or more spinose nodes across the middle 

 of the dorsal side, and by a row of smaller retral si)ines or 

 nodes around the posterior dorsal margin. 



Caudal platk short, triangular, produced behind into a 

 slender, acute, carinate spine, having a length equal to one- 

 half the abdomen; also two lateral movable s})ines, extend- 

 ing as far as the prolongation of the telson. Test thin. 



The largest carapace observed has a length of IS mm., 

 and a width of 10 mm. A single cercopod belonging to a 

 lai-ge individual has a length of 25 mm. A small entiie ex- 

 ample has a total length of 16 mm., of wliich 6 mm. pertain 

 to the carapace, mm. to the abdomen, and 4 mm. to the 

 telson and spine. 



This species is more highly ornamented than any yet de- 

 scribed, and is the only one of the genus observed in the 



