80 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
of the outlines of the group of Cystechinus allied to C. vestca. The specimens 
collected varied from a brilliant dark violet to a light claret color. 
The anal system is very large, placed well above the ambitus. On the actinal 
side, the primary tuberculation of the test is smaller and less crowded than in 
C. vesica. There are four genital pores in all the specimens collected; another 
feature distinguishing it from C. vesica. 
Station No. 3360, southwest of Mariato Point, in 1672 fathoms. 
[ «3374, southwest of Malpelo Island, in 1823 fathoms. 
ANANCHYTIDA, As. Gras. 
PHRISSOCYSTIS, A. Ace. 
This genus is allied to Paleeotropus and Paleobrissus in having like them a 
simple ambulacral system, without even the slight trace of petaloid arrangement 
found in Palzobrissus, The petals are perhaps even more like those of Cyste- 
chinus, Echinocrepis, Gonicopatagus, Calymne, and the like. At the actino- 
some, however, the phyllodes attain an extraordinary development, recalling 
those of Paleopneustes and Linopneustes. The apical system is compact, 
similar to that of the genera last named, and the primary spines are long and 
curved, recalling those of the same genera. 
Phrissocystis aculeata A. Ac. 
Plate XII. Figs. 1-7. 
Although not a single complete specimen of this species was obtained, a 
sufficient number of larger fragments were collected to enable us to reconstruct 
fairly accurately this interesting sea-urchin. Its general facies must have 
been similar to the species of Linopneustes and of Paleopneustes. The test 
is thin, covered with large distant primary radioles of uniform size. .The 
outline of the test must have been somewhat conical, the apex slightly ee- 
centric posteriorly, the oral plastron very prominent and flanked by the wide 
bare areas of the posterior ambulacra. The apical system compact, with four 
large genital openings ; the madreporic body covers the whole of the posterior 
part of the apical system, and surrounds the anterior genital pores. The ocular 
plates are small but distinct, with large pores. The smaller plates of the 
abactinal part of the ambulacral areas are bare, the larger plates carry first one, 
and at the ambitus there are from eight to ten distant primaries. In the odd 
interambulacrum there is a slight median furrow extending a short distance 
from the apex to the anal system. The whole test is covered with distant 
miliaries irregularly scattered over the coronal plates. The anal system is 
transversely elliptical and protected by a number of irregularly shaped plates; 
the phyllodes are greatly developed. The largest specimens must have been 
100 mm. in length, and 50 mm. in height, and from 80 to 90 mm. in width 
across the anterior half of the posterior interambulacral area. 
Station No, 3366, in 1067 fathoms. 
