560 



ZOOLOGY 



SECT. 



but the dorsal surface of the posterior thoracic and abdominal 

 regions : in order to bring the parts into their adult position, the 

 abdomen must be supposed to be lifted up and turned backwards. 

 In the meantime the post-mandibular appendages are formed 

 in regular order from before backwards : the eye-stalks appear 



stclrrv 



, 

 cibd. 



CCft 



Fi:s. 44."> ;md 446. Suctions of embryos of AstaCUS. A, Nauplius-stage (f?j. Fig. 444; 15, after 

 development of thoracic appendages ('/. Fig. 447). <ti>d. abdomen ; <tn. anus ; bi-. brain ; 

 cct. ectoderm ; ciid. cndndorin ; ent. ciitcron ; ht. heart ; //d.-. 1 . inusodcrm ; HU-S.' splanchnic 

 layer of mesodcrin ; intli. mouth ; /icdin. proctodseum ; *t<lni> stomodaeum ; t/i. nlni. tlxoracico- 

 abdominal rudiment ; v. no. <:d. ventral nerve-cord. (From Korschclt and Holder, after 

 Reichenbach.) 



(Fig. 447, A), as well as the labrum (/.), and a fold on each side 

 of the thorax, which is the rudiment of the; carapace (&>), and this 

 gradually extends dorsally until it meets with its fellow of the 

 opposite side and covers in the cephalothorax. The embyro now 

 consists of a nearly globular cephalothorax with a small abdomen 



