74 SCHIZASTER FEAGILIS. 
k 
Schizaster fragilis Agass. 
Quite a common species near the 100 fathom line, off the Xew England coast. 71-362 fathoms. 
For a list of Stations, see Bull. M. C. Z., VIIL, No. 2, p. 84, 1880. 
PI. XXV HI. Figs. S-U. 
There is considerable variation in the distinctness of the lateral fascicle as 
it passes nnder the anal system. In some cases it stops suddenly near the 
level of the anal system ; in others it can be itiintly traced as an indistinct, 
irregular anal fasciole ; in others the anal fasciole is most clearly marked. 
These differences do not depend on .size, but specimens from one locality are 
usually similarly affected. Small specimens measuring G mm. in longitu- 
dinal diameter are but slightly elliptical when seen from above, the anterior 
ambulacrum scarcely indented, and the lateral ambulacra still flush with the 
test. The actinal side is slightly convex, the outline seen in profile is 
hemispherical, the apex being nearly central ; the circular anal system, 
flush with the test, is placed high on the posterior extremity' of the test. 
Both the peripetalous and lateral fascioles are well marked as narrow bands 
of miliaries, indicating in a very rough way the future indentations of the 
course of the fascioles. In this stage the posterior ambulacra consist only of 
two pairs of pores, and are scarcely one quarter the length of the anterior 
lateral ambulacra. There is no trace as yet of any genital openings. The 
actinal opening is circular, without a posterior lip, and the posterior edge 
of the actinostome is jtlaced nearer to the central part of the actinal side 
than to the anterior edge of the test. 
In specimens measuring 10 mm. in length, the posterior lateral aml)ulacra 
are still flush with the test, with five pairs of pores; the anterior ambulacra 
are slightly sunken. The odd ambulacrum is more sunken than in the 
younger stage described. The madreporic body, which in the preceding 
stage was only pierced by a single opening, is now marked by live or six 
small openings. There is as yet no sign of any genital openings. The 
posterior extremity of the test is more vertically truncated ; the anal system 
is more elliptical, and placed at the upper angle of the posterior level of the 
test. The fascioles are somewhat broader than in the younger stage ; they 
vary in width, the angles of the ambulacra assuming more clearly already 
the general course they finally take in larger specimens. The actinal open- 
ing is now placed well towards the anterior extremity. The outline of the 
