602 L. H. GOUGfl. 



separated from the abdomen. The extremities are much 

 further advauced than those of the third stage and, except at 

 their bases, are devoid of yolk. In surface views one sees 

 the Anlage of the brain as two white spots at the front end 

 of the cephalothorax. On the sides may bo seen, at the 

 base of the fourth pair of extremities, a horseshoe-shaped 

 excrescence; this is the hiteral organ, first described by 

 Laurie as occurring in Phrynus; it is always covered by 

 a shred of some dark substance. 



The joints of the legs can already be distinguished, the 

 embryo at this stage greatly resembling the one given in the 

 drawing (figs. 1 and 1 a) less the eyes, and with a much 

 smaller amount of brain. 



There are six pairs of extremities to be observed. The 

 first pair, the cheliceree, now lie before and on both sides of 

 the mouth, and under the fold which carries the median 

 eyes; their bases lie fairly wide apart. They are double- 

 jointed, the second joints pointing towards each other, not as 

 in adults, parallel and pointing downwards ; this becomes 

 still more conspicuous in the fifth stage. 



The pedipalpi, too, begin near the same fold, to which, 

 indeed, their bases are attached, xit their bases they give 

 off a branch, the endopodite, which forms a kind of mandible. 

 As yet no thorns are to be found on the octopodite ; they 

 first begin to appear in the fifth stage. The ectopodite is 

 much larger than the endopodite. 



The third pair of extremities corresponds to the first pair 

 of walking legs in spiders ; here they are developed into 

 long whip-like legs, with probably only a sensory function. 

 They lie doubled up upon themselves, surrounding the pedi- 

 palpi, and with their tips reaching as far as between the 

 chelicerae. At the bases of this and the next posterior 

 extremity I have been able to find the coxal gland. The 

 next three pairs .of extremities are the walking legs ; they 

 are all of about the same length, and shorter than the whip- 

 legs. They are likewise doubled upon themselves, and their 

 free ends are tucked under the preceding legs, only the sixth 



