ME. H. M, BEEIfABD ON THE CHERlSrETID^. 411 



as I can ascertain, witli ScJdzonofus, in having the basal parts of 

 the pedipalps directly under, or ventrally to, the basal regions of 

 the mandibles, which form the " cephalic lobes " *. 



In this ventral position of the basal regions of the pedipalps, 

 the Chernetidse are more primitive than Scorpio, in which the 

 same parts have been forced up laterally by the crowding for- 

 ward of the legs towards the anterior end of the body. The 

 result of the arrangement in the Chernetidse is curious : owing 

 to the enormous size of the pedipalps, and the consequent deve- 

 lopment of their muscles, nearly half the ventral surface of the 

 cephalothorax is taken up by the coxal joints of these limbs 

 (fig. 2). The four leg-bearing segments, which are fused to- 

 gether at least ventrally, are entirely confined to the posterior 

 half of the cephalothorax. 



Although there is no waist or diaphragm as in so many other 

 Arachnids, there are very deep lateral infoldings of the skin 

 between the sixth and seventh segments (figs. 2 & 12, L). And 

 further, the ventral segmental constriction between the sixth 

 and seventh segments is very deep, which would allow the 

 abdomen to be raised. These may be the first beginnings of a 

 waist. 



The Chernetidse agree with Galeodes in possessing a rostrum 

 or beak, which consists essentially of twoparts, a dorsal "labrum " 

 and a ventral " labium " t- The former is flattened laterally; its 

 tip is thin-skinned, andin"05^'s^w?re museorum'" curiously divided 

 in the mediau line, so that in horizontal sections it looks as if it 

 were produced into two horns (fig. 5) ; this part is probably 

 sensory. The mouth is on the ventral surface, and closed by the 

 wedge-shaped labium which fits into the oral aperture as shown 

 in the transverse section (fig. 4). This pointed labium is appa- 

 rently quite rigid, and reminds us of the remarkable process 

 between the pedipalps of Phryni(,s, which may be a homologous 

 structure. Further, in Scorpio, short as the labium is, it is of 

 essentially the same shape when examined in serial sections. 



In Galeodes, the mouth is at the tip of the rostrum. In the 



* My use of this term is explained in a sliort note on the " Head of Galeodes 

 and the procephalic lobes of Araehnidan embryos," in the ' Zoologischer 

 Anzeiger,' no. 426, 1893. 



t I use these terms to indicate the homologies which I think are the most 

 natural. I cannot see what is gained by endeavouring to deduce the rostrum 

 from fused limbs (Croneberg (3)). 



32* 



