ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
55 
which he obtained from the stomach cavity of Geryonia ( Carmarina ) 
hastata . The stock was bifurcated, and covered with Medusa-buds of 
various ages. Some of these were liberated, and swam about in the 
characteristic Narcomedusa fashion. 
The stock consists of an axial part and the medusae which bud from 
it. The axis is not a simple tube, but exhibits irregular ramifications. 
F. E. Schulze’s observations on the minute structure were confirmed. 
Individual buds at different stages were carefully disposed and sectioned, 
and a series is described. It is difficult to refer the form to any of 
Haeckel’s families. In the absence of an annular canal, it is like one 
of the Solmaridae, but is distinguished by the Horspangen and other 
features. In other ways it approaches the Cunanthidte, but among 
these it seems almost to require a new genus. 
It is difficult to explain the relative simplicity of this form as the 
result of degeneration, for the gastro-vascular system is from the first 
a simple stomach, and of circular canal and radial canals there is not a 
hint. The position of the tentacles, which arise at some distance from 
the margin, developing along with and between the lappets, is another 
remarkable peculiarity. The author inclines strongly to the interpre- 
tation that a planula, sexually produced, settles down in the tissue of 
the Geryonia , and forms a stock which produces Medusae by budding ; in 
short, that there is a simple alternation of generations. A further con- 
sideration of this alternation of generations leads Dr. Maas to the view 
that the relations of the Narcomedusae to the other Craspedota are less 
close than has been hitherto supposed ; in fact, that Narcomedusae and 
the other Craspedota are only connected by a common root. 
Porifera. 
Flask-shaped Ectoderm and Spongoblasts of one of the Keratosa * 
— Mr. G. Bidder describes the ectodermal cells of what is apparently 
Cacospongia scalaris as having a flask-shaped form ; treatment with 
dilute osmic acid, followed by nitrate of potash and nitrate of silver, 
shows that the cells open on the surface in the centre of the silver areas ; 
the only nucleus connected with the silver area is the one lying in the 
base of the pendent cell-body. This completely justifies the inability 
of Schulze and other trustworthy investigators to find nuclei at a more 
superficial level, where the “ flat epithelium ” was usually supposed to 
exist. 
The spongoblasts of this sponge form a continuous tissue with the 
ectoderm cells, which they resemble in form and character. The 
appearance seen suggests that the apex of a conulus is a locus of 
attraction for ectoderm cells, and that the fibre is nothing more than 
the concentrated cuticle of a large number of such cells poured out 
round an intrusive foreign object. 
After a short discussion of Mr. Minchin’s recent observations 
Mr. Bidder states that it seems to be an established fact that in all groups 
of Sponges the flask-shaped epithelium does occur ; it, and not a flat 
epithelium such as lines the canals, is the structure most commonly to 
be met with. 
* Proc. Roy. Soc. Lond., lii. (1892) pp. 134-9 (3 figs.). 
