MR. H. M. BEEISTAED OK THE CHEElSrETID^. 413 



found also in the upper lip of Scorpio and of the Araneids (fig. 4). 

 The under lip is raised by a pair of muscles descending on each 

 side from the dorso-lateral sclerite of the basal joint of the 

 pedipalp. 



The muscles of the mandibles are, as is the case in all the 

 Arachnida, confined entirely to the " cephalic lobes," i. e. to the 

 region which in other Arachnids corresponds with the lobes 

 forming the so-called head of Galeodes *. 



Powerful muscles run from the sides and back of the cephalo- 

 thorax into the abdomen, serving to raise the latter, and perhaps 

 also to move it from side to side. 



There are seven pairs of dorso-ventral muscles in the abdomen, 

 commencing in the first abdominal segment. These muscle- 

 bands, which slope downward and outward, are attached dorsally 

 to the tergites on each side of the dorsal vessel or dorsal blood- 

 sinus, and ventrally to the sternites. They cause regular con- 

 strictions of the lateral diverticula of the alimentary canal 

 (fig. 6). 



The abdominal papillsa, through which the glands formerly 

 thought to be the spinning-glands open, appear as if they could 

 be raised and depressed, i. e. by raising the chitinous folds from 

 which they are differentiated (fig. 10). The muscles marked m^ 

 in the figure appear to be elevators, those marked m^ depressors 

 (found only for the posterior papilla). 



Histologically, the muscles are like all Arachnidan muscles ; 

 each fibre consists of a medullary axis of sarcoplasm with trans- 

 versely striated bands arranged radially around it as a cortical 

 layer. 



TJie Alimentary Canal. 



The alimentary canal offers many points of special interest. 

 Its general form has been already rightly described and figured 

 by Oroneberg. 



Inside the mouth, the passage is both dorsally and ventrally 

 finely striated transversely, as in the Araneidse. On leaving the 

 beak, the cesophagus suddenly swells into a sucking apparatus, 

 which has already been accurately described by MacLeod (5), 

 although I agree with Croneberg in disputing the rudimentary 

 condition of the organ. The dorsal expanding muscles are 

 attached to an apodeme between the mandibles and the pedipalps, 



* Cf. note on p. 411. 



