Z.y.l HUXLEY, ON THE MOUTH OV THE SCORPION. 



like those of the mandibles and maxilla} of Crustacea and Insects. It can 

 thus only be compared to these pieces ; but ought we to regard it as repre- 

 senting both the mandibles and the jaws, or only the mandibles, or the jaws, 

 either one or the other being supposed to be aborted?" 



With respect to both the main points contained in these 

 paragraphs, however, M. Blanchard subsequently makes 

 statements which seem difficult to harmonise with the con- 

 clusions enunciated. 



Thus, at page 41, I find : 



n The pharyngeal nerves are two pair. Those of the first take their origin 

 from the anterior and median edge of the cerebrum, and almost imme- 

 diately unite so as to form a single nerve, whose branches are distributed in 

 the upper portion of the buccal appendage. It is evidently the analogue of 

 the nerves of the labrum of insects." 



And, again, at page 60 : 



" Mouth and oesophagus. — The buccal orifice appears under the form of a 

 little transverse cleft, hidden under the chelicera above (au'demu) the 



median appendage, which has already been described (p. 19); its edges are 

 flexible, and are deprived of asperities. The oesophagus, which commences 

 in a slightly funnel-shaped pharynx, is delicate, short, and widened pos- 

 terity, so as to resemble what M. Leon Dufour calls the 'jabot' in iusects. 

 The oesophagus is held upon each side, towards its middle, by a line mus- 

 cular band directed backwards, and towards its point of union with the 

 stomach by a similar band directed forwards. These muscles are attached 

 to the sternal floor, formed, as is known, by the basilar pieces of the ap- 

 pendages. They serve to stretch the oesophagus either forwards or back- 

 wards, so as to facilitate deglutition. 



" The walls of the oesophagus are thin and smooth internally, and present 

 a few fine folds." 



In the figures (op. cit., pi. iv, figs. 1 and 6), which repre- 

 sent the anterior part of the alimentary canal, the oesophagus 

 is represented as a straight, taper tube, ending in the mouth, 

 without change of direction. 



At page 32, M. Blanchard states, under the head of — 



" Muscles of the bvccal appendage. — We have indicated the two, long, diver- 

 ging, apodemes of this piece (p. 19). Upon the base ><\' each of them is 

 inserted an elevator muscle, provided with two fixed attachments to the cc- 

 phalo-thoracic shield in front of and external to the median eyes (pi. ii, fig. 

 4<?eand fig. G a). By its contraction, this muscle causes the buccal appendage 

 to be elevated a little — a movement which takes place when the animal intro- 

 duces food into its mouth. A transverse muscle is attached to the twoapodemic 

 plates (pi. ii, fig. •]•/') ; it is this muscle which, acting either on the one 

 side or on the other, determines the Blight lateral movements of the buccal 

 appendage, tt is to be observed, thai this piece, solidly fixed between the 

 foot-jaws, sensibly involves the latter during the execution of its slight 

 movements." 



