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Y. The Nervous System. 
The nervous system is very concentrated as in most Acari and 
Åraneae, the ganglions being fused into a single one in the cephalo- 
thorax. There is no distinction between the supra- and the sub- 
oesophageal ganglion, as the commissures are broad and short. The 
»brain" thus becomes one single mass pierced by the oesophagus 
(pl. VI fig. 1—2 mn), higher in front than to the back. A transverse 
section (pl. VI fig. 7 nm) through the brain in front shows that 
the organ here is almost twice as high as broad. Behind the 
supraoesophageal ganglion it is much broader than high. The 
brain is placed in front and below, just above the sternum. In 
section I have seen the nerves to the ambulatory appendages and 
most distinctly the maxillary and antennal nerves, the latter seem 
to arise from the commissure. The cortical layer of deep-staining 
cells is very well developed, chiefly in front and below. Behind, 
in the upper curvature of the brain, there is no cortical layer 
(fig. 1 2»). 
8. The Alimentary Canal. 
The mouth is placed at the tip of the pseudocapitulum under 
the free. part of the labrum. Just under the mouth, between the 
two small lateral lobes and merging into it, a chitinous tube 
arises which may be followed along the lower side of the pharyngeal 
tube to its base. The pharynx and the oesophagus are not sharply 
marked off from each other. The first part within the pharyngeal 
tube is most naturally called the pharynx; the remaining part which 
penetrates the brain and debouches into the intestine, the oeso- 
phagus. 
The pharynæ (pl. VI fig. 5 p) is a narrow chitinous tube, at 
least in front tricarinate and thus similar to that found in Haemo- 
gamasus (Michael 11 p. 310 pl. 35 fig. 73). One keel is directed 
downwards, the two others upwards and outwards. More proximally 
each keel is divided into two short ones, but it is always easy to 
Vidensk. Meddel. fra den naturh. Foren. 1904. El 
