ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
737 
inclines to tlie view that it forms the germiniferous part of the ovary ; 
hut, as he remarks, there is no such structure in any other family of the 
Acarina, and we can get therefore no assistance from analogy. The 
author enters into the details of minute structure, into which our want 
of space prevents us following him. With the lyrate organ a sacculus 
and ringed tubes appear to be correlated. A very remarkable variation 
from the accepted type of the female generative organs of the Gamasinae 
is recorded in Sejus togatus. 
e. Crustacea. 
Gammarini.* — The twentieth of the splendid monographs issued 
under the general title of ‘ Fauna und Flora des Golfes von Neapel * is 
a treatise on the Gammarini, by Signor A. Della Yalle. As is usual in 
these monographs the whole subject is most exhaustively dealt with, and 
the illustrations are of the high order to which Dr. Dohrn has now 
accustomed us. 
Embryology of Cumacea.| — Mr. P. Butschinsky has a preliminary 
notice of his work on the development of the Cumacea. In Iphinoe 
meeotica the cleavage of the egg is centrolecithal. All the segmenta- 
tion nuclei, which are surrounded, in the centre of the egg, by radial 
masses of protoplasm, make their way to the surface and finally form a 
homogeneous blastoderm. 
On the ventral side of the egg there now appears a blastodermic 
thickening, the foundation of the germ-band ; in this three separate 
thickenings may be noted — the paired anterior optic lobes and an 
unpaired one behind, which contains a large number of cells (meso- 
endoderm). These inner cell-masses become differentiated into three 
foundations — the yolk-cells which migrate with the yolk, the meso- 
dermal and the endodermal cells. 
The proctodaeum is formed before the stomodseum and has the appear- 
ance of a very long tube. The liver is developed very early, and forms 
two tubes composed of large cells. The central nervous system is laid 
down as an ectodermal thickening at the time when the anterior extremi- 
ties are being formed. In its earlier stages it is paired, but the halves 
gradually unite and form an unpaired cord, in which eighteen to nineteen 
ganglia are developed. The unpaired eye is developed from two separate 
thickenings of the hypodermis of the most anterior optic lobe, and 
undergoes a complicated metamorphosis. The first sign of the heart is a 
compact collection of mesodermal cells on the dorsal side. The genital 
organs appear as paired outgrowths of the mesoderm. The dorsal organ 
is developed very early as an oval ectodermal aggregation of cells; 
it does not disappear until after all the organs of the animal are 
formed. 
Germinal layers of Cladocera.J— Dr. P. Samassa, who has already 
investigated the history of the summer egg of Moina rectirostris , now 
gives an account of his observations on Daphnella brachyura and Daphnia 
hyalina. If we compare the formation of the germinal layers in the 
Cladocera with that of Branchipus , we find that total has been replaced 
* ‘Fauna u. Flora des Golfes von Neapel &c. xx. Gammarini.’ Berlin, 1893, 
xi. and 948 pp., Atlas of 61 pis. t Zool. Anzeig., xvi. (1893) pp. 386 and 7. 
X Arcli. f. Mikr. Anat., xli. (1893) pp. 650-88 (4 pis.). 
