Tl: \ III VI \ 



441 



next four are provided with provisional appendages ; while the 

 last six arc without appendages. The further features of this 

 stage which deserve notice are (i) the appearance of a shallow 

 depression (st) the rudiment of the stomodjcum between the 

 hinder part of the two procephalic lobes ; (2) the appearance of 



!'!<;. 2OO. FOUR STAGES IN THE DEVELOPMENT OF AGELENA LABYRINTH1CA. 



A. Stage when the ventral plate is very imperfectly differentiated, pr.c. primitive 

 cumulus. 



B. Ovum viewed from the side when the ventral plate has become divided into 

 six segments, ck. segment of cheliceni- imperfectly separated from procephalic lobe ; 

 fd. segment of pedipalpi. 



C. Ventral plate ideally unrolled after the full number of segments and 

 appendages are established, it. stomodxum between the two pnc-oral lobes. 

 Ik-hind the six pain of permanent appendages are seen four pairs of provisional 

 appendages. 



D and . Two views of an embryo at the same stage. D ideally unrolled, 

 seen from the side. it. stomodonim ; <h. chelicerac ; on their inner side is seen 

 the ganglion belonging to them. pd. pedipalpi ; f>r.f. provisional appendages. 



raised areas on the inner side of the six anterior appendage- 

 bearing segments. These are the rudiments of the ventral 

 ganglia. It deserves to be especially noted that the segment of 



