xiv LIST OF ILLUSTRATIONS 



FIG. PAGE 



159. Strongylocentrus drb'lachiensis 344 



160. Dorsal view of the dried shell of the common British Sea- 



urchin, Echinus esculentus ...... 345 



161. A glandular or gemmiform pedicellaria from Echinus 



esculentus 346 



162. Dissection of Echinus esculentus so as to show the structure 



of "Aristotle's lantern" 347 



163. Diagram of a longitudinal vertical section of a Sea-urchin . 348 



164. Transverse sections through the madreporite and the radius 



of Echinus esculentus 351 



165. Dissection of a Sea-urchin so as to show the course of the 



alimentary canal 352 



166. The oral field or peristome of Echinus esculentus , . 353 



167. The aboral system of plates, or periproct and calyx of 



Echinus esculentus 355 



168. Dissection of a Sea-cucumber, Holothuria tubulosa, so as to 



show the arrangement of the viscera .... 358 



169. A Feather-star, Antedon acoela ...... 361 



170. Diagram of a longitudinal vertical section of the common 



Feather-star, Antedon rosacea 362 



171. A stalked Feather-star, Rhizocrinus .... 363 



172. Ventral view of a larva of a Holothurian . . . . 364 



173. Shell of a fossil Brachiopod, Terebratula semiglobosa . 371 



174. Section through the shell of Waldheimia Jlavescens . . 371 



175. Dissection of Waldheimia australis so as to show the in- 



ternal organs 372 



176. Longitudinal vertical median section of Argiope neapolitana 373 



177. Portions of two Polyzoan colonies . 376 



178. Longitudinal vertical section of Plumatella fungosa . . 377 



179. An avicularium of Bugula 379 



180. Ventral view of Sagitta hexaptera 382 



181. . Transverse sections of Sagitta bipunctata and of Spadella 



cephaloptera . 383 



182. A Dolichoglossus kowalevskii ...... 387 



183. Longitudinal vertical section of Glossobalanus . . . 388 



184. Longitudinal horizontal section of Glossobalanus . . 389 



185. Amphioxus lanceolatus seen from the left side . . . 391 



186. Views of the velum and of the oral cartilages of Amphioxus 391 



187. Diagrammatic longitudinal section of an embryo of 



Amphioxus 392 



188. Anterior region of a young Amphioxus seen from the left side 393 



189. Diagrammatic transverse section through the pharyngeal 



region of a female Amphioxus . . . . . 394 



190. Transverse section through the intestinal region of a 



young Amphioxus 395 



