NOTES ON L.M.B.C. ASTEHEROIDEA. 239 
hemal ring (Pl. XX XVIII, fig. 2; Pl. XXXIX, fig. 1, ahr) 
from which arise the ten genital strands (gs), two at each 
interradius. Cuénot’s (6) studies of the development of 
the genital organs of Asterids have led him to the conclu- 
sion that they are simply the largely developed ends of 
the genital strands, and that the cells of the strands give 
rise to ova or spermatoblasts. With the exception of the 
gastric strands, the whole hemal system is enclosed in 
pevihemal canals, with which the axial perihemal canal 
is continuous. I have already said that at its oral end the 
central plexus becomes continuous with an oblique per- 
forated septum. This latter imperfectly separates the 
circum-oral periheemal canals, into the inner of which the 
axial perihemal canal opens, while the outer unites the 
perihemal canals of all the rays (Pl. XXXIX, fig. 1, pe, 
ope). Serial sections in which the septum appears show 
that at many points it presents lacunar spaces to which 
the term “‘ oral blood-vascular ring”’ has been applied (PI. 
XXXVIII, fig. 3, cohr), the lacune being described as 
vessels. They are, however, simply lacunar spaces, and 
except when distended with coagulum, or with amoeboid 
cells, are not easy to see. It has been asserted that they 
and the hemal lacunez of the rays are nothing more than 
spaces occupied before decalcification of the specimen by 
calcareous skeletal matter. Jam satisfied, however, that 
such is not the case, for the connective tissue basis upon 
which the skeleton is formed is always left intact after 
decalcification, and no such connective tissue 1s seen here. 
The perihzemal canals of the rays are, like the circumoral 
canals, imperfectly separated by a vertical septum which 
is continuous with the oblique septum already described. 
These also present lacunar spaces, frequently distended 
with coagulum, or with amceboid cells, and are the radial 
