202 General Notes. [ February, 
considerable number of portions; the central cleavage-masses are 
round or polygonal, the peripheral ones stellate. Yolk cleavage 
now takes place, the yolk breaking up into pyramidal masses, as 
in the Decapoda, these masses carrying portions of protoplasm 
upon their apices; the segmentation is not dichotomous; the 
number of pyramids was always the same, and the only dif- 
ference between the young and the perfect pyramid consists in at 
indefiniteness of outline in the apex of the former. The simu 
taneous origin of the masses is not an impossible circumstance, 
and is explained by the action of the central protoplasm in draw- , 
ing into itself the superincumbent yelk. The protoplasm-mass® 
of the yelk now sink into the pyramids which form the primary 
endoderm, and the central protoplasm-masses come to the sur- 
face of the ovum and form the primary ectoderm, In the Chilog- 
natha, judging from Polydesmus, the method of formation of the 
blastoderm more resembles that of the Crustacean and Ara 
nida; the yelk cleavage appears to have been correctly described 
by Metschnikoff. The blastoderm of Geophilus consists at first 
of large, pale, very thin cells, dividing very rapidly so as to "= 
in the course of twenty-four hours, a number of very small ¢ 
which are, however, smaller on one side of the ovum than wpe 
other; on this side the primitive streak appears, beginning ù 
anterior end, which develops the first segments and appends” 
before the hinder portion is clearly defined. Before the ry 
ance of the primitive streak the mesoderm is divided © ested 
the small-celled ectoderm, and at the same time nuclei, 10V a 
rived from the nucleus of the ovum, and to have bith 
mained at the center. The mesoderm, like the primitive ® ids 
evelops first in front. The conversion of the yo ne takes 
into endoderm, 7. e., into the epithelium of the mid-gut, nest that 
place when the embryo is fully formed; it commences ane the 
stage which Professor Metschnikoff did not observe, 4” 
same time as the beginning of flexion of the embryo. the tras : 
ihe two preceding paragraphs have been taken from of the 
lation in the Journal of the Royal Microscopical so i 
author’s abstract (published in the Zool. Ansieger, V 5 iane” 
later stagės are described in detail, with sections, both tre feet! 
and longitudinal, and views of the complete embry? g a 
stages; with some sketches of the later embryo m figure? 
The structure of the nervous system is described ane y. A 
including the brain of Scolopendra, in a comparati gee 
translation of the entire memoir would be most desirable 
_ New Cave Aracunips.—The following cave cos 10 0f 
 Phalangidæ and Nemastomatidæ are interesting addis a 
cave-fauna. oa T 
- Obisium caricola, n. sp—This is an aberrant specie’ 
ae 
