1902.] ' A^fATOMY OF THE PEDIPALPI. 185 



that is given of the organ, however, suggests an airangement of 

 diverticula quite different from that obtaining in the specimens 

 dissected by Blanchard, Tarnani, and myself. It represents a wide 

 diverticulum as arising, on each side, m front of the descending- 

 trunk of the aorta, and extending backwards on each side of the 

 horizontally lying portion of this vessel to the posterior end of the 

 prosomatic cavity, giving off the five cfecal diverticula along its 

 course. Thei-e is nothing to indicate the formation of the annular 

 space through which the aorta and the two muscular tendons of 

 the entosternite pass. 



Tarnani says the foregut of Thelyphonus is like that of the 

 Spiders. This seems to be an overstatement of the case. In 

 the Spidei-s, the dorsal muscle of the pre-cerebral pharjaigeal 

 sucker extends to the median line of the anterior portion of the 

 carapace, not to a chitinous entosclerite as in Thehjphonus. More- 

 over, the wall of the oesophageal portion of the foregut is much 

 more thickly chitinized and moi'e rigid than in Thelyphonus, and 

 is supplied with a well-developed post-cerebral sucking-apparatus 

 lying on the upperside of the entosternite and worked by 

 powerful lateral muscles which attach it to this j)late, and by a dorsal 

 muscle which passes from its chitinous dorsal wall thi'ough the 

 aortic space of the "stomach" to the median entapophysis of the 

 carapace. 



In many stiuctui'al chaiacteis the Amblypygi ai-e intei-mediate 

 between the Urotricha (Thelyphonida?) and the Spiders. This 

 is stiikingly the case with regai'd to the foi'egut. The pharyngeal 

 portion is nai'i'ower and less strongly chitinized than in Thely- 

 phomts, and the muscles of the pi-e-cerebral sucker extend dorsally 

 to a median entosclerite rising fi'om the membrane above the base 

 of the camarostome, and laterally to the coxa? of the chela?. The 

 latter, however, are not immovably united like those of Tlielypjlionus^ 

 but move freely in a horizontal plane, and compress the suckei- 

 between their inprojecting ends. The oesophageal portion of the 

 foregut is a sinuous tube with rigid chitinous walls, like that of 

 the Aranese ; and behind the biain it forms a highly developed 

 sucking-apparatus, with dorsal muscle extending to the under surface 

 of the carapace and lateral muscles passing to the entosternite. 

 This organ differs from that of the Spiders only in position. 

 Instead of i-esting upon the entosternite and being attached 

 to its upperside by transverse muscles, it lies in fi'ont of it in the 

 " pharyngeal notch," the lateral muscles extending to the anterior 

 border of this plate. Thus in position it resembles the less highly 

 specialized organ of Thelyphonus. 



The midgut expansion, Math its diverticula, more resembles that 

 of some Spidei's than of the Thelyphonida?. As in these groups, 

 the primaiy saccular diverticulum extends forwai'ds on each side 

 of the descending aorta, forming a channel through which this 

 vessel continues its downward course, and the muscle from the 

 post-cerebral sucker and the two obliquely directed apophyses 

 from the entosternite ascend to the median depi'cssion on the 



