ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
473 
agilis Leidy, Microjoenia hexamitoides g. et sp. n., of the family Lopho- 
monadidse ; Pyrsonympha flagellata sp. n., Holomastigotes elongatum g. et 
sp. n., of the family Pyrsonymphidae. 
Origin and Formation of Chitinous Investment of Larvae of 
Libellulidae.* — M. J. Chatin is of opinion that this chitinous covering 
is formed by the epidermic cells, not as a secretion, but by an altogether 
special process which compels us to consider the investment as directly 
formed by the protoplasm of the cells being transformed into chitinized 
layers. In this way plates are formed, the thickness of which increases 
progressively, and in which the trabecular structure of the hyaloplasm 
may be made out. As they extend to the neighbouring elements, these 
products of differentiation provoke their fusion and profoundly modify 
the texture of the epidermic or chitinogenous layer. M. Chatin thinks 
that the facts which he brings forward ought to modify the current 
ideas as to the mode of formation of the integument of Insects, which is 
generally looked on as a secretion which is at first liquid and hardens 
on contact with air. They are not without value as indicating the 
importance of the study of cuticular structures from the point of view 
of Zoological Histology. 
S. Arachnida. 
Hydrachnidae.l — Prof. P. Kramer, in investigating the larval forms 
of Hydrachnidae, has been led to divide the genera into three subdivisions. 
The first includes Eydrachna, the second the majority of fresh-water 
mites, the third Diplodontus , Hydrodroma , Eylais, and probably Limno- 
chares. The last subdivision shows most affinities with Trombidiidae. 
Herr E. Piersig J describes a minute new species of Arrenurus, which 
he names A. bisulcicodulus. Of Neuman’s new genus Bradybates he has 
discovered a German species B. truncatus. A number of larval forms 
are also described. 
Circulation of Blood in Young Spiders.§ — M. M. Causard has 
examined the circulation in the young of fifteen genera of dipneumonous 
Araneida. His results differ in some points from those obtained by 
Claparede with Lycosa. The recurrent branch given off from the 
cephalic arteries conveys the blood into a lacuna which occupies the 
median part of the upper surface of the cephalothorax, and not, as he 
thought, into a true canal. In Spiders which have undergone their first 
moult and are still transparent, ramifications of the cephalic arteries 
may be noticed which were not observed by Claparede. The appearance 
of ramifications which do not exist immediately after birth is very 
interesting, as showing that the arterial system is capable of complica- 
tion, and of attaining the development described by Blanchard and by 
Schneider. The blood which reaches the heart does not all pass by the 
lungs, but may circulate in the integument. The venous blood circulates 
in a very extensive system of lacunae. 
Sensory Structures of Solpugid8e.||— Dr. Ph. Bertkau describes 
peculiar sensory organs on the upper surface of the last joint of the palps 
and first pair of limbs in species of Solpuga, Galeodes, and Batames. 
* Comptes Rendus, cxiv. (1892) pp. 1135-8. 
f Zool. Anzeig., xv. (1892) p. 149. 
§ Comptes Rendus, cxiv. (1892) pp. 1035-8. 
ft Zool. Anzeig., xv. (1892) pp. 10-3 (1 fig.). 
t Tom. cit., pp. 151-5 (3 figs.). 
