ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
175 
in fairly regular rows, in tlie posterior portion of the embryonic streak ; 
(3) a small plate of cells which Bergh (erroneously) calls the endoderm 
disc ; and (4) the so-called yolk-cells, a layer of large vesicular cells 
lying on the yolk. 
These yolk- cells, which Bergh leaves unheeded, surround the yolk, 
increase in size, become pyramidal in form, and absorb the yolk. But 
before the formation of the stomodaeum, some of the yolk-cells separate 
off in the region where that invagination will occur ; these form the 
midgut epithelium. The other yolk-cells subsequently degenerate. 
What Bergh calls the endoderm disc turns out to be the rudiment of the 
gonads. 
Wagner gives this comparison between the development of Schizo- 
pods and Arachnids (Scorpion and Phalangidae) : — 
ScilTZOPOIfeV 
Wtello- Midgut Repro- 
phagous epithelium ductive 
cells cells 
Arachnida 
General endoderm 
and gonadrudiinent 
\itello - Midgut Repro - 
phagous epithelium ductive 
cells cells 
Small Crustacea from New Mexico.* — Mr. C. L. Herrick reports 
that the valley of the Rio Grande contains pools in which, after heavy 
rain, there appear large numbers of Phyllopoda. Although the species 
are limited there is no lack of individuals. The numbers of Moina which 
appear in fresh rain pools is enormous, and amongst them is M. recti- 
rostris. All the Calanidae and Harpacticidse found were new. The 
author describes several new species, for some of which he makes the 
new genus Marshia. 
Development of Kidney and of General Cavity in Cirripedia.f — 
M. A. Gruvel, who found that in adult Cirripedes there was no com- 
munication between the kidney and the general cavity, has examined the 
arrangements which obtain in the young. He has studied a series of 
Lepas pecturata. There is in the larval stage a quite small cavity which 
communicates directly with the exterior by a pair of orifices, and which 
evidently represents the general cavity of the adult. At the bottom of 
this cavity there is a small mass of cells with a narrow central lumen, 
which is the commencement of the renal gland. As the general cavity 
increases in size the lumen of the gland increases more and more, and in 
quite young individuals, shortly after their escape from the larval test, 
there is a distinct communication between the general cavity and the 
kidney. As the animal grows, renal cells become more and more differ- 
* Zool. Anzeig., viii. (1895) pp. 40-7 (28 figs.), 
t Comptes Rendus, cxix. (1894) pp. 1228-30. 
