166 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Molluscoida. 
$. Bryozoa. 
Critical Notes on Polyzoa* — The Rev. T. Hincks lias published 
the second part of his critical notes on Polyzoa, in which he deals with 
classification ; the paper is too critical and controversial to be abstracted, 
but it appears to be of great value in the present state of the classifica- 
tion of this difficult group. 
Development of Bryozoic Colony in Fertile Statoblasts.t — Herr F. 
Braem describes the statoblast from which a colony of Bryozoa arises as 
a mantle of ectodermal cells, which inclose a yolk-mass in whicli there 
are a number of nuclei. This mass is the product of those funicular 
cells which constitute the young statoblasts. While the protoplasm 
contained in the yolk becomes bounded off into cells around the nuclei, 
which, for the most part, lie close to the ectoderm, the basis is laid down 
of an internal epithelium which spreads out between the ectoderm and 
the yolk-mass. It grows by the deposition of new cells as well as by 
the ingestion of yolk-substance. In one region the ectoderm of Cristatella 
shows a marked change ; as its cells increase considerably in size and 
height they form a cylindrical epithelium which soon gives rise to a 
definite germinal disc ; this covers the greater part of the shell, but with 
a tendency to lie on one side. This disc is the rudiment of the first 
polypide of the future colony ; its peripheral margin becomes more and 
more contracted as a circular groove sinks in from without ; at the point 
where the margins of the groove fuse with one another the cervical 
portion of the bud is developed, and it is by means of this that the bud 
remains in connection with the body-wall. A further series of changes 
result in the differentiation of an anal and oral region in the bud. In 
front of the anus the rudiment of the central nervous system appears in 
the form of a slight depression of the inner layer of the bud, which 
corresponds to the outer ectodermal layer of the wall of the statoblast. 
Still nearer the mouth there is the sharply marked incision between the 
arms of the lophophore, which does not yet reach the oral base of the 
central cone ; here, too, is an invagination which will form the oeso- 
phageal portion of the digestive tract; it curves towards the closed end 
of the anal tube, which has already attained a considerable size. The 
later processes are essentially the same as those seen in budding in the 
stock. 
The author promises a full account of his investigations. 
Arthropoda. 
a. Insecta. 
Evolution of Papilionidse.J — Prof. G. H. T. Eimer has given a 
practical illustration of his conclusions as to the origin of species,§ in 
rt treatise on the varieties and species of Papilio. Taking the four 
* Ann. and Mag. Nat. Hist., v. (1890) pp. 83-103. 
t Zool. Anzeig., xii. (1889) pp. 675-9. 
X ‘ Die Artbildung und Verwandtschaft bei den Schmetterlingen. Eiue sys- 
tematische Darstellimg der Abandernngen, Abarten und Arten der Segelfalter- 
ahnliohen Fonueu der Gattung Papilio,’ 8vo, Jena, 1889, pp. 243 (23 tigs.); also an 
atlas with 4 folio coloured plates. § See this Journal, 1889, pp. 31-3. 
