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SUMMARY OF CURRENT RESEARCHES RELATING TO 
ings in two specimens found by himself in Victoria, he was at first 
inclined to think that he had discovered a new species.* The close and 
critical examination of the colour markings which he has since made has 
shown him that this is not the case. 
5. Arachnida. 
Lung of Arachnida.t — M. L. Berteaux. has made a study of the 
lungs of Arachnida. He describes the upper surface of the pulmonary 
plates of the dipneumonous forms as being covered with chitinous tigella 
with free ends ; these tigella are united at their base by a plexus with 
polygonal meshes which is formed by the cuticle. In Mygale the tigella 
anastomose at their tops, and the whole constitutes a trellis- work. 
The free edge of the plates of the Dipneumona has a “marginal 
palisade ” formed of anastomosed tigella. In Euscorpius flavicaudis the 
structure of the pulmonary plates is almost exactly like that of the 
dipneumonous spiders. In Buthus europseus the two lamellae which form 
a plate carry the same chitinous processes ; in Scorpio indicus the plates 
are divided into two zones, one of which is naked, while the other carries 
spines which are analogous to those of the Dipneumona. The walls of 
the pulmonary cavity carry various chitinous processes. All the varied 
kinds of processes found on the plates or in the walls are analogous. 
The straight bars with free ends, which are borne by the pulmonary 
plates of Epeira diademata, appear in the embryo in the form of pro- 
tuberances of the cuticle, and, in the course of development, become 
enormously elongated. 
The two chitinous lamellae which form a pulmonary plate are, in 
both Spiders and Scorpions, united by cells ; these cells are separated 
by large spaces, in which blood circulates, and they reach, more or less, 
to the surface of the cuticle. These interlamellar cells are capable of 
contraction, and their alternate contraction and dilatation results in the 
movement of the blood which is contained in the lamellae. The move- 
ments of the cells may also allow of the entrance and exit of a small 
quantity of air into the lung, but they are insufficient to account for 
the ventilation of the organ, which is due to other and as yet unknown 
causes. 
The author regards the pulmonary plates of Arachnida as similar 
to the branchial plates of various Crustacea, and especially of the 
Poecilopoda. 
Embryology of Pycnogonida.J — Mr. T. H. Morgan thinks that the 
evidence afforded by the developmental history of the Pycnogonida 
points to their affinities with the Arachnida. The process of multipolar 
delamination to form the endoderm seems to be common to the two 
groups ; it is represented in its greatest simplicity in the majority of the 
Pycnogonida, while Pallene furnishes an analogy to the changes which 
an accumulation of food-yolk will cause in this process, and renders a 
comparison with the Arachnida quite possible. Other common points 
are the formation of an opaque area ( Pallene ) at the place where the 
* This was called P. insignis in a preliminary account published in the ‘ Victorian 
Naturalist’ for April 1890 (sic). f La Cellule, v. (1890) pp. 255-317 (3 pis.). 
X John Hopkins Univ. Circ., ix. (1890) pp. 59-61. 
