ZOOLOGY AND BOTANY* MICROSCOPY, ETC. 
591 
Coxal Glands of Arachnida.* — Dr. E. Sturany describes these 
organs which occur in all the orders of Arachnida, though with great 
diversity of form and size. In Limulus there is a four-lobed mass 
between appendages 2-5 ; the scorpion has a roundish packet at the base 
of the third and the fourth walking legs ; in the Pseudoscorpionidea 
there are tubes in the region of the last three appendages ; in the 
Solifugae there is on each side a single long and much coiled tube ; in 
the Pedipalpi there are packets of considerable size in the region of the 
last three legs ; the spiders have diffuse coiled tubes in the Tetrapneu- 
mones, simple or quite rudimentary sacs in the Dipneumones ; the 
Phalangiidae have much coiled tubes, which open in spacious ventral 
sacs ; finally, the mites have only traces of tubes. The glands have a 
striated cortex and a granular nucleated internal layer. The coxal 
glands of Limulus , Scorpions, Pseudoscorpionidea, Tetrapneumones, and 
Phalangiidae are homologous and may be derived from a pair of 
nephridia opening on the fifth appendage ; but the glands of the 
Dipneumones lie in the region of the third appendage. Therefore two 
pairs of nephridia may be represented in Arachnida. 
e. Crustacea. 
Eyes of Crustacea .f — The results of the studies of Wanda Szcza- 
winska may be shortly stated thus. The eye of Gammarus is provided 
with a hypodermis which is formed by a single layer of flattened cells 
not differentiated for each retinophore. In Astacus the cells of the 
hypodermis are grouped in pairs and cover the whole of the outer 
surface of a retinophore. The calyx and style in Gammarus and Bran- 
chipus , the calyx, style, and pedicel in Astacus, unite to form a continuous 
hyaline axis which reaches from the cornea as far as the basal membrane, 
to which it is attached by means of hyaline filaments. 
In Gammarus three kinds of pigment-cells are grouped around each 
hyaline element of the eye, and are arranged in whorls of five each ; 
these cells are provided with very distinct nuclei, which are arranged in 
three rows set in different planes. In Astacus the three kinds of pig- 
ment-envelope are arranged thus ; the first covers the anterior part of 
the retinophore ; it is formed by four cells placed at the four edges of 
the calyx ; they give off filaments, one anteriorly and one posteriorly which 
serve to attach them to the cornea and to the basal membrane. The 
second envelope, or retinula of Grenacher, is formed of a verticil of 
seven cells, the nuclei of which are large and are placed at their anterior, 
enlarged extremity ; four of these cells are shorter than the other three. 
The cells of the third set are placed near the basal membrane, and are 
distinguished from the first by their yellow crystalline contents ; they 
appear to be seven in number. 
From the experiments that were made it would seem that in the 
pigment-cells which surround the calyx and the style, the pigment, in 
darkness, is placed in the distal part of the eye ; in the cells which 
surround the pedicel the pigment is in the proximal part and near the 
basal membrane. In light, the pigment of the cells which surround the 
calyx and style moves toward the optic nerve, so as to become more 
* Arbeit. Zool. Inst. Univ. Wien (Claus), ix. (1891) pp. 129-50 (2 pis.). 
t Arch, de Biol., x. (189$$ pp. 523-66 (2 pis.). 
