602 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
limbs and makes them oscillate slightly ; when, therefore, the limbs are 
extended and unsupported, simultaneous oscillations are produced, by 
means of which one may count the oscillations of the heart. 
Coxal Gland of Scorpion.* — M. P. Marchal considers that this 
organ is of the same nature as the antennary gland and the shell- 
gland of Crustacea. The medullary substance contains two sets of 
lacunae which are very distinct, though they have hitherto been con- 
founded ; some are glandular lacunae, and the glandular epithelium 
which often fills the lumen is ver^ similar to that which is found in the 
saccule of the antennary (green) gland of Crustacea. Others are blood- 
lacunae ; these are wide, and may be at once distinguished from the 
others by the fact that they are bounded by a proper membrane, which 
separates the glandular epithelium from the blood-fluid, and they are 
often filled by a coagulum which has a dotted appearance. The glan- 
dular lacunae open into a wide central space which plays the same part 
as the central cavity of the ramified saccule of marine Decapod Crustacea, 
and is in direct communication with the long duct that forms the 
cortical substance. The author compares this with the arrangement 
found in the green gland of Crustacea. He regards the view of 
Lankester that the epithelium of the saccule is formed of differentiated 
connective tissue, and the cavity as part of the coelom, isolated and 
adapted for excretion, as being confirmed by his investigations ; for the 
glandular lacunae of the medullary substance of the Scorpion may be 
considered as spaces hollowed out in the midst of a diffferentiated 
connective tissue. 
The three sets of organs here regarded as of the same nature may be 
all looked upon as part of a metameric series. 
Classification of Mites. f — Dr. Trouessart’s essay on the classification 
of Acari is noticed by “ C. M. W.” He divides the sub-class Acaroidea 
into two orders, the Acarina, in which the abdomen is entirely united 
with the cephalothorax, and the Vermiformia, in which the abdomen is 
distinct from the cephalothorax and ringed, and in which there are no 
tracheae. The Acarina are divided into three sub-orders, Prostigmata, 
Metastigmata, and Astigmata, in which the tracheae, respectively, open 
on the anterior portion of the body, at the posterior part, or are absent. 
The first sub-order contains the four families of Trombidiidae, Hydrach- 
nidae, Halacaridae, and Bdellidae ; the second, the Gamasidae, Ixodidae, 
and Oribatidae; and the third, the Sarcoptidae. The Vermiformia are 
either octopod, with four pairs of feet, as the Demodicidae, or tetrapod 
as the Phytoptidae. 
Notes on Ixodidse.^ — Sig. A. Batelli publishes a preliminary 
account of some of his investigations on the structure and functions of 
Ixodidae. The alimentary canal of Ixodes, with its buccal and suctorial 
organs and its digestive region, is first described. Digestion occurs es- 
pecially, but not exclusively, in the lateral compartments. The hepatic 
caeca are at once storage regions and digestive. An account is given of 
* Comptes Rendus, cxv. (1892) pp. 191-3. 
f Araer. Natural., xxvi. (1892) pp. 712-3. 
X Bull. Soc. Entomol. Ital , xxiii. (1892) pp. 218-35 (1 fig.) ; Monitore Zool. 
Itul., ii. (1891) pp. 78-84 and 98-104. 
