ZOOLOGY AND 130TANY, MICROSCOPY, ETC. 
483 
sented by a hermaphrodite gland, and in its general structure the 
generative apparatus has a striking resemblance to that of certain 
embryonic Gastropods. It cannot, however, be denied that, in many 
essential points, Rhodope does not exhibit a Molluscan organization. 
The blood-vascular system, the heart, the foot, the shell, are as much 
wanting in the embryo as in the adult ; and there is no velum. It is 
more doubtful what stress is to be laid on the absence of a radula. 
On the whole, then, we may say that Rhodope is anatomically most 
allied to the nudibranchiate Gastropods, while in its developmental 
history it is connected with the Turbellaria. At present it would seem 
to be impossible to assign a precise systematic position to this creature, 
and it would be well if a close study could be made of its embryology. 
The only thing we can say with certainty is that Rhodope is not a 
Turbellarian. 
Gastrotricha.* — Dr. F. v. Wagner gives an account of what is known 
(through Zelinka and others) in regard to these small organisms. They 
are small worm-like animals, without a retractile rotatory apparatus at 
the anterior end ; with two ciliated bands along the whole ventral 
surface ; with two coiled water-vascular canals, each with a long rod- 
like ciliated lobe and a separate aperture in the middle of the ventral 
surface; with a simple cerebral ganglion in part still in the ectoderm, 
simple muscle-cells, paired ovaries, a muscular, nematode-like, fore-gut 
without jaws, a straight mid-gut without glands, a pear-shaped hind-gut, 
a rectum, and a dorsal anus ; and with a primary bo ly-cavity. The sub- 
order Euichthydina (with a forked tail) includes Ichtkydidae (without 
spines), viz. Ichthydium and Lepidoderma, and Chaetonotidse (with 
spines), viz. Chsetonotus and Chsetura. The suborder Apodina (without 
a forked tail) includes Dasydytes and Gossea. 
After weighing opinions, the author concludes that the Gastrotricha 
cannot be united with Rotatoria, but that they belong to a common stock 
and are nearly related. 
Echinoderma. 
Development in Asterina gibbosa.f — Mr. E. W. MacBride has a 
preliminary notice of his observations on the development of the dorsal 
organ, genital raehis and genital organs in this Starfish. His studies 
have confirmed the accuracy of his earlier observations on Amphiura 
squamata. The axial sinus of the starfish into which the stone-canal 
opens is obviously homologous with the relatively less developed ampulla 
of the Ophiurid ; in both animals the peculiar cells of the dorsal organ 
are derived from the peritoneal epithelium, but subsequently by a 
process of invagination become shut off from it ; hence the so-called 
axial sinus of Amphiura corresponds to the canal in the dorsal portion 
of the “heart” of Asterina. The aboral sinus is homologous, and its 
undulating course in Amphiura is evidently due to the way in which the 
abactinal surface has grown in between the actinal radii in Ophiurids ; 
this mode of growth forces the madreporite and the stone-canal round to 
the ventral side, while the aboral sinus is pulled out into five inter- 
radial ventral loops. 
* Biol. Centralbl., xiii. (1893) pp. 223-38. 
f Zool. Anzeig., xvi. (1893) pp. 169-73 (4 figs.). 
