XIV LIST OF ILLUSTRATIONS. 



FIG. 



1 06. Cross section through A scar is .... 



107. Illustrating the structure of a Nematode 



108. Trichinae in muscle, about to be encapsuled after Leuckart 



109. Trichinae in muscle, encapsuled. There may be 12,000 in 



a gramme of pig's muscle after Leuckart 



no. Earthworms ....... 



in. Anterior region of earthworm after Hering 



112. Transverse section of earthworm .... 



113. Reproductive organs of earthworm after Hering 



114. Stages in the development of earthworm after Wilson 



115. Arenicola marina ...... 



1 1 6. Anterior part of nervous system in Arenicola after Vogt 



and Yung ...... 



117. Dissection of lob- worm from dorsal surface . 



1 1 8. Cross-section of Arenicola after Cosmo vici 



119. Development of Polygordius after Fraipont 



1 20. Parapodium of " Heteronereis " of Nereis pelagica after 



Ehlers ....... 



121. Free-living Polychaete (Nereis cultrifera) 



122. Transverse section of leech after Bourne . 



123. Alimentary system of leech after Moquin-Tandon . 



124. Dissection of leech after Bourne .... 



125. A nephridium of leech after Bourne 



126. Development of Sagitta after O. Hertwig. Illustrating 



formation of a body cavity by pockets from the archen- 



teron ; also the early separation of reproductive cells . 



I26A. Diagram of a Rotifer (Hydatina) after Plate . Facing 



127. Actinotrocha or larva of Phoronis2,itei Masterman 



128. Phoronis ....... 



129. Diagram of an Ectoproctous Polyzoon (Plumatella} 



130. Interior of Brachiopod shell, showing calcareous support for 



the "arms" after Davidson . . . .251 



131. Pluteus larva of Ophiuroid, with rudiment of adult after 



Johannes Mliller ..... 253 



132. Star-fish . . 256 



133. Alimentary system of star-fish after Muller and Troschel . 257 



134. Diagrammatic cross-section of star-fish arm after Lud wig . 259 



135. Ventral surface of disc of an Ophiuroid ( Ophiothrix fragitis] 



after Gegenbaur . . . . .261 



136. Apical disc of sea-urchin . . 263 



137. Dissection of sea-urchin ..... 265 



138. Spicules of Holothurians after Semon . . . 268 



139. Dissection of Holothurian (Holothuria tubulosa) from the 



ventral surface . . . . . .271 



140. Diagrammatic vertical section through disc and base of one 



of the arms of Antedon rosacea after Milnes Marshall . 273 



141. Stages in development of Echinoderms after Selenka . 276 



142. Appendages of Norway lobster .... 285 



143. Section of compound eye of Mysisvulgaris after Grenacher 287 



144. Longitudinal section of lobster, showing some of the organs 289 



145. Male reproductive organs of crayfish after Huxley . 292 



