24 • ME. M. I/AITEIB ON THE 



TJnderneatli tlie heart lies the gut, whiela merits a somewhat 

 full description. It commences at the mouth with a long 

 stomodseum, which is lined by a thin chitinous cuticle. The 

 anterior part of this stomodseum tas muscles passing dorsally 

 and laterally from it to be attached to three chitinous processes, 

 which run back from the epistoma (camerostome) nearly as far 

 as the brain. There is no appearance of a dilatation into a 

 sucking-stomach such as is found in the Scorpion. A transverse 

 section of the stomodseum (PI. III. fig. 2 a) shows a folding-down of 

 the dorsal side like the typhlosole of a worm. The sides of this 

 down-folding are straight and covered with cuticle of the same 

 thickness as that lining the walls of the stomodseum, while the free 

 ventral edge of the fold is irregular in form and covered by much 

 thinner cuticle. The only function I can suggest for this fold 

 is that it acts in some way as a valve to assist in sucking. 



Just behind the brain the stomodseum opens into the mesenteron 

 (figs. 1 and 2). The first (thoracic) portion of this is expanded 

 into wide lateral diverticula, which extend over the brain in front 

 and the coxal gland at the sides. Each diverticulum is divided 

 into five lobes, the cavity of most of which seems to be a simple 

 space. The front diverticulum, however, and perhaps portions 

 of the others, is cut up by a- meshwork of tissue (fig. 1 a), the 

 object of which is, I imagine, to aff"ord a greater surface. The 

 histology of this region I have not been able to study in any 

 great detail ; but it is evident that the thoracic diverticula are 

 very difierent in structure from the abdominal diverticula or 

 " liver." In addition to these lateral diverticula, there are two 

 median ones from the ventral surface (fig. 2, m.d.g.). These 

 pass through the entosternite, one going through the large oval 

 anterior aperture in it and the other through the smaller posterior 

 aperture (fig. 4). "Ventral to the entosternite, these diverticula run 

 forwards between it and the thoracic ganglion as simple tubes. 



The middle portion of the mesenteron opens into the large 

 diverticula of the digestive gland or " liver." There appear to 

 be four pairs of these diverticula, the last one being very much 

 the largest and opening from the gut about the fourth free 

 segment. Behind the fourth segment the gut runs as a narrow 

 tube as far as the seventh segment, and then expands into the 

 large hourglass-shaped stercoral pocket (fig. 3). The peculiar 

 shape of this stercoral pocket is due to its being compressed 

 by the dorso-ventral muscles of the eighth free segment. The 



