576 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
and the almost constant presence of some representative in every catch, 
except in the restricted area mentioned above. Taking detailed account 
of certain species, Dr. Maas discusses their geographical distribution, 
and endeavours to map out certain pelagic districts ; he allows, of course, 
that more experience is required before we can be secure about these, 
but points out how his districts agree with those which other investi- 
gators of Plankton-organisms have defined. In regard to the vertical 
distribution, the author is again very guarded in his statements ; he 
indicates the difficulty of the problem and the various methods of solving 
it ; his facts, so far as they go, prove that a number of superficial pelagic 
forms may retreat several hundred metres beneath the surface, perhaps 
avoiding warmth, increased salinity, the force of the waves, and the 
like. If there are any deep-sea Craspedote Medusae, they must be, he 
thinks, only Polypomedusae. 
Finally, Dr. Maas alludes to various interesting problems : — How 
are the periodic variations connected with sexual periods ? Whether are 
Trachylinae or Leptolinae the more primitive ? Is the gelatinous mesogloea 
a protective adaptation, a “ starvation-tissue,” or an economical surface 
of insertion for the musculature ? What are the bionomic relations of 
the Craspedota to other organisms and to the general Stoffwechsel of the 
ocean ? 
New Veretillid.* — Dr. G. H. Fowler describes, under the name of 
Cavernularia malabarica , a new sea-pen from Calicut, which is remark- 
able for the great breadth of the rachis, and the sharpness of the cur- 
vature by which this is marked off from the stalk. It would seem to be 
most nearly allied to C. luetkeni. 
Origin of Sex-Cells in Hydractinia.f — Miss M. Bunting, who has 
investigated the origin of the sex-cells in Hydractinia and Poaocoryne, 
as well as the development of the former, finds that the gonophore of 
Hydractinia is formed by a protrusion of the ectoderm and endoderm, 
caused by a multiplication of cells in both layers. The ova appear to 
be of endodermal origin, while the spermatozoa are of ectodermal origin. 
The medusa-bud of Podocoryne has a similar origin to the gonophore, 
and the generative products have the same origin as in Hydractinia. 
The two polar globules leave the surface of the egg of Hydractinia 
at tbe beginning of segmentation ; this is total and equal ; the endoderm 
originates by multipolar delamination, and the ccelenteric cavity is due 
to breaking down of endoderm cells ; the mouth is formed by this cavity 
breaking through to the exterior. The tentacles appear as solid endo- 
dermic outgrowths surrounded by endoderm. The hydrorhiza appears 
first as a stolon-like outgrowth, but later becomes tubular. 
Porifera. 
Generic Nomenclature of Bowerbank’s British Sponges.! — Dr. R. 
Hanitsch refers to the universal refusal of Spongologists to accept the 
late Dr. Bowerbank’s generic nomenclature and classification. He has 
attempted to assign all the species described by that writer to their 
proper genera, as the latter are at present accepted. 
* Proc. Zool. Soc. Lond., 1891, pp. B76-9 (1 pi.), 
t Journ. Morpbol., ix. (1894) pp. 203-36 (3 pis.), 
j Trans. Liverpool Biol. Soc., viii. (1894) pp. 173-206. 
