ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
621 
showing the variations which the members of the group exhibit in the 
presence or absence of upper arm-plates, tentacle-scales, tooth-papillae, 
radial shields ; in Ophioteresis alone of known existing Ophiuroids 
there are no under arm-plates. In Ophiosciasma they are imperfect. 
He reverses the order of arrangement of Astrophiurae proposed by 
Mr. Lyman, and proposes a grouping which agrees with that of 
Ljungman. 
Attention is also drawn to the large size of the calycinal plates 
in a young Ophiuroid. 
Development of Amphiura squamata.* — Mr. E. W. MacBride has 
studied the development of the genital organs, pseudo-heart (ovoid gland) 
and axial and aboral sinuses in this Ophiurid. In embryos of 200- 
220 p in diameter, in which the arms are still undeveloped, the 
coelom is filled by a mass of mesenchyme. Covering the external wall 
of the stone-canal there is a single layer of nuclei; this layer is the 
first rudiment of the pseudo-heart. Proliferation soon commences in 
this layer. When the embryo has a diameter of 300 p, the first rudi- 
ments of the axial sinus are visible. The author has been able to dis- 
tinguish three separate rudiments, all of which have been confounded 
by most observers under the name of axial sinus. Ludwig, however, has 
distinguished one, probably of enterocoelic origin, from the axial sinus 
proper. One sinus is formed as an involution of the coelom underneath 
the rapidly growing rudiment of the pseudo-heart ; and another may be 
described as a chink between the aboral part of the stone-canal and the 
body-wall. This last soon closes, embraces the basal part of the stone- 
canal, and at a later period, extends up on to the sides of the pseudo- 
heart. The second sinus forms the rudiment of the aboral “ pseudo- 
haemal sinus ” ; it soon closes, and the large cells in the aboral part of 
the pseudo-heart migrate along with it to form the genital rachis. The 
gonads are swellings of this rachis, and the testes develope more 
rapidly than the ovaries. 
Where proper precautions are taken to ensure the penetration of the 
osmic acid, the structure of the pseudo-heart appears to be that of a 
uniformly staining plasma, supported by a fibrous network with 
numerous cells ; no lacunae are visible. There is no trace of either 
oral or aboral haemal rings. What have been taken to be vessels seem 
to be appearances due to the cell-plasma of the cells on the dorsal side 
of the nerve-cord. 
Asteroidea of the ‘Prinz Adalbert.’! — Dr. M. Meissner has a report 
on the eighteen Starfishes collected at various places during the voyage 
of the German ship ‘ Prinz Adalbert ’ : Echinaster cylindricus from 
Callao, Goniodiscus sanderi from Zanzibar, and Astropecten latespinosus 
from the Inland Sea of Japan are described as new. Most of the species 
are well known. 
New Antedon from Mauritius. J— Prof. F. Jeffrey Bell describes a 
new species of Comatulid — A. emendatrix — from Mauritius, which be- 
longs to the group called by the late Dr. H. Carpenter the “ A. palmata 
* Zool. Anzeig., xv. (1892) pp. 231-7 (2 figs.), 
t Arch. f. Naturg., lviii. (1892) pp. 183-90 (1 pi.). 
x Ann. and Mag. Nat. Hist., ix. (1892) pp. 427 and 8 (1 pi.). 
