1885.) Zoölogy. IOII 
This result is also confirmed by the examination of photo- 
graphs of fresh pieces, for then can be easily distinguished thir- 
ty-five myomeres and, besides, a region occupying the outer 
fourth of the tail, where the limits are no more- visible across the 
skin. But the sections prove to us that in this last quarter, con- 
trary to the opinion of Ecker and of M. His, the mesoderm is 
divided with the greatest clearness into a double series of somites 
which extend to the last extremity of the tail, but presenting, it 
is true, dimensions regularly decreasing up to the thirty-eighth 
somite, which does not measure more than thirty-seven microns 
in diameter. 
This fact is in no way teratological; it is plainly confirmed by 
several other embryos which I possess, all perfectly normal and 
of ages slightly different. 
ith the exception of the two last, all the caudal vertebrz 
have a blastema of a cartilaginous body similar, except in its 
dimensions, to that of any other vertebra of the series. The two 
last are only indicated by myomeres, perfectly distinct from the 
rest. The extremity even of the tail is formed by the termination 
of the medullary tube, only covered by the skin, The dorsal 
cord also extends very near this éxtremity. 
The last caudal vertebrze have only a very ephemeral existence ; 
already in embryos of 12™™ in length, viz., six weeks old, the 
thirth-eighth, thirty-seventh and thirty-sixth vertebre become 
confounded in a single mass, and the thirty-fifth itself is not per- 
fectly limited. An embryo 19™™ in length has no more than 
thirty-four vertebra, the thirty-fourth evidently resulting from 
the fusion of the last four; at this period the tail as a whole is 
already much less prominent. ; 
It results from these facts that the human embryo during the 
fifth and sixth week of its development, is provided with an un- 
doubted normal tail which in form is regularly conical, elongated 
and which deserves, under all relations, the name which I have 
given it. This organ, evidently deprived of all physiological 
utility, should be classed in the number of representative organs. 
—Professor H. Fol, in Comptes Rendus de l Acad. Francaise, Pune 
7 
an Echinanthus. As the ambulacral pores are arranged in rows 
which are not closed or quite parallel, and which show a tendency 
to spread at their distal end, and as the under surface, though 
with the ambulacral sutures of Echinanthus, has not those sutures 
converted into conspicuous grooves, Professor Bell makes it the 
type of a new genus. It is found upon the eastern coast of Aus- 
tralia ——As one of a series of contributions to the systematic 
arrangement of the Asteroidea, Professor F. J. Bell (Proc. Zool. 
VOL. XIX.—NO. x, 66 
