l-EUDOSCORPIOXES. 



29 



The further differentiation of the embryo is characterised by the 

 early and pronounced development of the future anterior end of the 

 body ; this appears as a great accumulation of cells belonging to 

 the inner layer of the blastoderm. A pair of marked swellings 

 appear on either side of this region, and from each of these a large 

 truncated appendage soon arises (Fig. 16 ^4). These processes are 

 the rudiments of the pedipalps which are here, as in Scorpio, the 

 first limbs to appear. They are still in a very primitive condition, 

 the inner yolk-mass extending far into them (Fig. 16 A and B). In 

 front of the limbs, towards the ventral surface, there is a swelling 

 which, even at this early stage, is distinguished by its strong muscu- 

 lature, and consequently has a striped appearance (Figs. 16 yl and B, 

 /•, 17 ^1). This is the rudiment of a provisional organ — a kind of 

 sucking proboscis (Fig. 16 C) which serves for attachment and for 



Fig. 1(3.— A and E, larva of Chelifer; C, provisional proboscis of an older stage (after Metsch- 

 nikoff). A, ventral aspect ; B and C, from the side, ah, abdomen ; d, yolk ; <j, brain ; p, 

 the four limbs ; pd, pedipalps ; r, proboscis (provisional larval organ). 



taking in food. The embryo leaves the egg at this stage, having 

 previously undergone a larval ecdysis. A fine cuticle, which 

 occupies a peculiar position between the bases of the two limbs, 

 becomes detached from the embryo. The larva, when hatched, at 

 the youngest stage shown in Fig. 16 A, has the muscular proboscis, 

 the truncated pedipalps, and the rudiment of the abdomen directed 

 forward. The proboscis, which is regarded as a modified upper lip, 

 already seems to function as a sucker, for the larva attaches itself by 

 means of this organ to the ventral surface of the mother. The 

 proboscis lengthens considerably at a later stage, and becomes applied 

 to the ventral surface of the larva, lying between the limbs (Fig. 16 

 B). Barrois has described a provisional oral aperture situated 

 between the pedipalps. There are also, according to Barrois, 



