IJSrVEETEBEATA 



FIQ. 



163, 



PAGE 



" Megalopa " larva of the Crab PiZMmm!«s, dorsal view . ■ ■■ 215 



164. Two views of first post-larval stage of Mupagurus bernhardi, corresponding 



to the Megalopa stage of Brachyura . . • • .216 



165. Two stages in the development of a Stomatopod larva . . .217 



166. Two later larvae of Stomatopoda ...■■• 2J8 



167. Larva and adult female of Pori!M?wo?i mffl«)iffl(^is . . . .219 



168. Adult female of Portunion inaenadis with appendages dissected out . 220 



169. Three stages in the segmentation of the egg of AgeUna . ■ ^ .222 



170. Surface views of the developing egg of Agelena lalnjrinthica, showing-the 



primitive streak and the primitive cumulus . . . .223 



171. Section through the primitive streak of AgeUna to illustrate the forma- 



tion of the germ layers . • . ■ • • _ • 



172. Two views of embryo of Agelena at the period of maximum extension of 



the ventral plate {i.e. before reversion has begun). The coelomic cavities 



are seen by transparence and are represented by lighter shading . 225 



173. Two sagittal sections through embryo of Agelena of different ages, but 



previous to reversion ..•■.-• 226 



174. A portion of a sagittal section of Agelena labyrinthica ■ . .227 



175. Two views of embryos of ^fifeiraa undergoing reversion . . .227 



176. Transverse sections through the heart of Agelena labyrinthica in two 



stages of development ....-.• ^^° 



177. The embryo of .^(/eZuma when reversion is complete . . . . 228 



178. Longitudinal section through part of the abdomen oi Agelena labyrinthica 



in order to show the origin of the genital organs .... 



179. Two sections through the developing stercoral pocket and Malpighian tubes 



of Agelena labyrinthica ....•■• 



180. Sagittal section through the hinder part of the abdomen of Agelena 



labyrinthica to show the hinder part of the mid-gut developing in 

 connection with the stercoral pocket ..... 



181. Longitudinal section through the abdominal appendages of an embryo of 



Agelena labyrinthica in order to show the origin of the lung book 



182. Surface views of the cut-off abdomen of three embryos of Agelena 



labyrinthica of different ages in order to show the modifications under- 

 gone by the abdominal appendages ..... 



183. The condition of the brain in the embryo of Agelena after reversion has 



taken place ......... 



184. Sections through the developing eyes of ^^«fe»a . 



185. Two sagittal sections through embryos of the spider Theridion maculatum 



in two succeeding stages of development ..... 234 



186. Horizontal section through abdomen of an advanced embryo of Agelena 



labyrinthica in order to show the division of the yolk into lobes by septa 235 



187. Ventral view of an embryo of Limulus longispina, twenty-one days old . 237 



188. The Trilobite larva of XimitZMS ...... 238 



189. Two transverse sections through the " germinal disc," or developing area, of 



the egg of the Scorpion Euscorpius carpathicus in two stages of development 239 



190. Ventral view of embryo of the Scorpion Euscorpius carpathicus showing 



segments and appendages ....... 239 



191. Ij3,rv3, o{ Ascorhynchus minutus ...... 242 



192. Dorsal view (optical frontal section) of the embryo of Macrobiotus . 243 



193. Portion of a sagittal section through the developing egg of Doryphora 



{Leptinutarsa) decemlineata before the formation of the blastoderm . 246 



194. Surface view of the egg of Donacia crassipes at the conclusion of blastoderm 



formation '. . . . . . . . . 247 



229 

 230 



231 

 231 



232 



233 



234 



