1885.) Zoölogy, 409 
difference in development between the Mediterranean and Ros- 
coff specimens to the difference of conditions, the former sea be- 
ing without heavy tides and powerful currents, so that the larve 
can safely issue into the water at an early stage. Dr. Senden- 
feld claims, in Zool, Anzeiger, Jan. 26, to have discovered a scat- 
tered system of mesodermal nerve-cells in’ several kinds of 
sponges. 
Mollusks—After a study of the morphology of Rhabdopleura 
from specimens obtained at Lervik, near Bergen, Norway, Pro- 
fessor E. R. Lankester does not decide whether the form is poly- 
zoan or molluscan, but inclines to the view that both it and 
Cephalodiscus are degraded lamellibranchs. The colony consists 
of branching tubes, built of a series of rings, each of which is 
separately secreted and added to its predecessors by the so-called 
buccal shield or pre-oral lobe of the polypide. A completed 
branch ends in an upstanding polyp-tube, while in a growing 
branch the axis runs beyond the last erect polyp-tube. The axial 
tube is divided by septa into segments, one corresponding to 
each polyp. When a bud reaches a certain stage of development 
it breaks through the wall of its chamber and grows outwards at 
a sharp angle. . Occasionally it atrophies, leaving a sterile cham- 
ber. The buccal shield or disk is locomotive as well as secretive, 
and is covered with fine cilia, which occur also on the lophopho- 
ral filaments of the arms right and left of it. In the center of 
the ringed caulotheca or tube is the axial stalk which connects 
and bears the polyps. This is soft in the polypides, hard on the 
stem, but every hard portion is formed by the shrinkage of the 
soft stalk and the development of a cuticle. An internal skele- 
ton exists in the lophophore and in the axis. The embryology 
of this curious form is as yet unknown, nor is it known whether 
the sexes are distinct or the colony persistent from year to year. 
More Pleurotomide. Mr. E. A. Smith describes (Aun. and 
Mag. Nat. Hist, Nov., 1884) thirty additional species of this 
group.——In the same magazine (Oct.) Dr. R. Bergh has a paper 
upon the affinities of Onchidia. After an examination of the 
structure of various organs, the writer arrives at the conclusion 
that “the Onchidia agree with the Pulmonata in the structure of 
the nervous system, in the existence of a lung and of a parenchy- 
matous kidney, in the presence of a peculiar pedal gland, and in 
various peculiarities of the generative system. They branch off 
from the Pulmonata; they are Pulmonata which have adapted 
themselves to an amphibiotic or marine mode of life. 
Crustaceans—Among new forms of Crustacea dredged by the 
Albatross in 1883, are an ally of Ethusa, taken in 1496 to 1735 
fathoms, a species of Galacantha M. Edwds., in 1479 fathoms, two 
forms of Pentacheles, between 843 and 1917 fathoms, Notostomus, 
a Palemonid, six inches long and of an intense dark crimson, in 
