Structure of the Pseudoscorpion>i. 317 



under the bark of trees, led me to undertake as thorougli an 

 anatomical investigation as I was able to make of this repre- 

 sentative of a group of animals which is still but imperfectly 

 known. Besides the above-mentioned species I liad at ray 

 disposal a few specimens of a rarer undetermined species of 

 Cliernes^ as also of Chelifer granulatus^ C. Koch. 



The buccal aperture is on the lower surface of a rostrum 

 which unites the basal joints of the maxillte from above, and 

 of which the anterior part consists of a nearly transparent 

 chitinous membrane, which projects in the form of an elongate 

 ovate upper lip. The margins of this lamella, which are folded 

 downwards, are soldered together anteriorly in the middle 

 line ; but further back they separate from each other and are 

 furnished here with a fine denticulation. In the space 

 between them a second strongly boat-shaped compressed 

 lamella is received like a lower jaw, and its margins are also 

 finely denticulated. The whole in profile has a certain 

 resemblance to a shark's tail. Posteriorly the two lainellai 

 pass over into the wall of the short pharynx, which is situated 

 immediately beneath the basal part of the rostrum. The 

 strongly chitinized wall of the pharynx is produced into four 

 ridges, so that the narrow lumen has a four-rayed transverse 

 section. Numerous muscles which extend partly between 

 the ridges of the pharynx and partly between the latter and 

 the walls of the body serve as dilators, while the contraction 

 of this sucking-apparatus appears to be left to the elasticity of 

 its walls. 



Its posterior extremity abuts directly upon the central 

 mass of the nervous system, which in nearly all the conditions 

 of both external and internal structure resembles that of certain 

 Acarida {E^Ia'is, Trombidium) — a spherical brain seated upon 

 a broad, quadrangular, thoracic ganglion ; but I could not 

 observe anything of the fine accessory nerves of the extre- 

 mities which occur in many Arachnida. On the other hand, 

 in Chernes, which, as is well known, is blind, there are a 

 pair of fine nerves at the same part of the brain from which 

 the visual nerves originate in tiie above-mentioned Acarida. 

 The thickness of the nerve-cell layer around the inner 

 granulo-fibrous substance in the whole of tiie cephalothoracic 

 ganglion is also remarkable. The cephalothoracic ganglion 

 is traversed by a very narrow oesophagus^ which enlarges in 

 the form of a tunnel immediately behind the brain, and then 

 at once narrows again to form the intestinal tube. This 

 small dilatation forms tlie true stomach of the animal ; like 

 the intestine, it is lined with a clear small-celled epitlielium, 

 and communicates directly with three great hepatic sacs, two 



