ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
595 
Vermes. 
a. Annelida. 
Homology of Pedal and Cephalic Appendages in Annelids.* — 
M. A. Malaquin is of opinion that the cephalic appendages of Annelids 
are morphologically comparable to the pedal appendages ; he finds that 
the dorsal and ventral setigerous rami may undergo modifications and be 
converted into cirriform appendages which may be sensory ; the cephalic 
lobe is regarded as a single segment, the appendages of which, though 
profoundly modified, may be homologized with the different parts that 
make up the parapodia of normal segments. 
Development and Morphology of Parapodia in Syllidinae.f — M. A. 
Malaquin has made an examination of the appendage in this group of 
Polychseta. He looks on the organ when at its maximum size as being 
composed of, in the order of their development — a ventral branch, a 
dorsal cirrus, a ventral cirrus, and a dorsal branch. This is sometimes 
found, but only in segments provided with swimming setaB. The most 
general composition of the parapodium is ventral branch, dorsal and 
ventral cirri. Reduction may result in the loss of the last of these, or 
may, as in Procerastea , go further, so that there is merely a ventral 
swelling whence emerge setae. In this genus, however, there is, at the 
time of reproduction, a series of complications due to the tardy develop- 
ment of the appendages in sexual forms. 
A comparison of the morphology and development of the parapodia 
shows that the phenomena of retrogression of the constituent parts in the 
Syllidinae follow the inverse order of their embryological appearance. 
These facts confirm the view of Hallez, that in the development of an 
organ which has begun to retrograde the organ goes through a reduced 
number of stages ; so that, in place of passing through stages a, b, c, and 
d, it only reaches c, then b, and finally a. 
Reproductive Organs of Diopatra.J— Mr. E. A. Andrews had his 
attention attracted by peculiar strings of green cells which occur 
abundantly in the body-cavity of Diopatra magna sp. n. and D. cuprea Bose, 
found at Beaufort, North Carolina. On investigation they were found 
to be ovarian cells liberated along with the ova, and remaining for a 
time attached to them as peculiar processes. It is difficult to imagine 
what the function of these bodies can be. There is no reason for sup- 
posing that the ova derive nourishment directly from them, for a firm 
egg-membrane, which would prevent the ingestion of entire cells, is early 
developed, and, later on, they are entirely absent. Mr. Andrews suggests 
that the cell-strings may be mechanical supports which serve to keep 
the ova separate and well surrounded by the nutrient fluid while floating 
about. The most similar case is to be found in Bonellia , where the 
ovum is armed at one point of its periphery with a collection of cells of 
no apparent use. 
A diagnosis is given of D. magna , the young of which often construct 
small tubes on the outside of those of the adult. 
* Comptes Rendus, cxiii. (1891) pp. 155-8. f Tom. cit., pp. 45-8. 
X Journ. of Morphology, v. (1891) pp. 113-22 (2 pis.). 
