556 W. WOODLAND. 
Nove ON A STAGE IN THE SCLEROBLASTIC DEVELOPMENT OF THE 
PLATE-AND-ANCHOR SPICULES OF SYNAPTA INHAERENS. 
Whilst staying at Plymouth in the spring of 1904 I was 
able to obtain, with the kind assistance of Dr. E. J. Allen, 
about a score of young specimens of Synapta inhaerens. 
I hoped with these specimens to be able to ascertain the 
scleroblastic development of the characteristic spicules of 
these animals, but, young though the specimens were, all the 
spicules were more or less fully formed, and I only succeeded 
in procuring what is probably the final stage of growth. 
Since I am not aware that any scleroblasts have previously 
been figured in connection with the spicule, I think it worth 
while publishing the sole result that I have obtained. } 
The accompanying text-figure (text-fig. 4) shows well the 
position of the plate-and-anchor spicules in the body-wall 
of Synapta. As is already well known, the length of the 
anchor, curiously enough, is disposed transversely to the 
long axis of the animal, and the anchor encloses with the 
plate an angle which is fairly constant. It is possible that 
Ostergren (8), following Quatrefages, is right in considering 
that the anchors aid in the locomotion and burrowing of the 
Synapta, but the suggestion is no explanation of the evolution 
of these curious structures. 
Semon (9) has supplied excellent figures illustrating 
the morphogenesis of the plate-and-anchor spicules of S. 
inhaerens. As I have above remarked, all the spicules I 
observed were adult in form, and the Synaptas, having been 
treated in the same manner as the Cucumarias, showed well 
the cell-plasm and nuclei associated with them. As illus- 
trated by figs. 45 and 44, the most conspicuous features of 
the spicule are the two elongated strands of protoplasm 
containing many nuclei which run on either side from the 
arms of the bow to the handle. This strand thickens at its 
bow end, forming a blob at the point of the arm, and the 
