ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
461 
calities make a summary of an already condensed narrative exceedingly 
difficult; we therefore restrict our report to noticing the important 
result gained — that there is a morphological unity in the placentation 
of Rodentia. 
A Duck with Drake’s Plumage.* — Mr. A. Willey has examined a 
female of Anas boschas var. dom. L., whose plumage closely resembled 
that of a male. The oviduct was normal in length and form, except that 
the wall of the lower part was thickened and the lumen divided into 
two. There was no mesovarium. The ovary was much reduced ; no 
follicular epithelium was recognizable ; all the ova were invaded by 
wandering cells, and were being absorbed. For two years the bird had 
been kept in the Zoological Institute at Freiburg, and had laid no eggs ; 
but its original owner stated that it had laid for several years, and that 
it had exhibited male plumage from its youth. Is this then a case of a 
female organism inheriting some of the secondary sexual characters of 
the male ; or was the male plumage correlated with a degeneration of 
the essential female organs ? Mr. Willey points out that a sure answer 
cannot be given without knowing more definitely about the bird’s life- 
history. 
Development of the Teleostean Vertebral Column. | — Dr. C.Scheel 
has studied this in embryos of Bhodeus amarus, trout, salmon, &c., and 
comes to the following conclusions : — 
In Teleostei there is a regular, single-layered, chorda-epithelium. 
The notochord is surrounded by a non-cellular sheath, and outside this 
by a non-cellular elastic membrane. In Bhodeus the superior arch and 
the parapophysis of each side have a common origin in an aggregation 
of cartilage cells lateral to the notochord. In the trout there is apparent 
discontinuity between superior arch and parapophysis, but the inter- 
vening perichondrium unites them. In Bhodeus the superior arches unite 
in a median process, as is the case also posteriorly in trouts. Medianly 
and anteriorly, however, the arches in the trout run parallel, and small 
transverse pieces form a (primitive) bridge between them. Cartilaginous 
fin-rays extend along the whole dorsal surface far beyond the definite 
fin-regions — a fact which proves the primitive dorsal extension of the 
fin. In Bhodeus there is, especially in the anterior region, a very great 
development of cartilage around the notochord — forming a thick ring — 
the common basis of superior arches and parapophyses. In trouts this 
mass is much reduced. The inferior caudal arches are ventrally directed 
parapophyses, but not true haemapophyses. Indeed, these are not 
developed in Teleosteans, except perhaps in the anterior trunk of 
Bhodeus. The ribs are abjointed from the parapophyses, and those of 
Teleosteans must be regarded as homologous with those of Amphibians. 
Development of the Pancreas.J— Dr. E. Goeppert has studied this 
in embryos of the salmon-trout. The organ makes its first distinct 
appearance in embryos twenty-one days old. A dorsal rudiment — a 
direct outgrowth of the gut — is first seen, but by the thirtieth day there 
are two other outgrowths on the ventral surface. These arise from the 
* Ber. Nat. Gesell. Freiburg i. B., vi. (1891) pp. 57-61 (1 pi. and 2 figs.). 
t Morphol. Jahrb., xx. (1893) pp. 1-47 (3 pis.). 
j Tom. cit , pp. 90-111 (6 figs.). 
2 k 2 
