LIST OF ILLUSTRATIONS. 
. Cross section through Ascarés . . 
. Illustrating the structure of a Nematode , 
. Trichine in muscle, about to be encapsuled—after Leuckart 
. Trichine in muscle, encapsuled. There may be 12,000 in 
a gramme of pig’s muscle—after Leuckart 
. Earthworms. . . . 
. Anterior region of earthworm—after Hering A 
. Transverse section of earthworm. . . 
. Reproductive organs of earthworm—after Hering . 
. Stages in the development of earthworm—after Wilson F 
. Arenicola marina 
. Anterior part of nervous system in Arenicola—after Vogt 
and Yung ‘i ‘ 
. Dissection of lob-worm from “dorsal surface ‘ 
. Cross-section of Arenzcola—after Cosmovici 
. Development of Polygordzus—after Fraipont . . 
. Parapodium of ‘‘Heteronereis” of MVerezs pelagica—after 
Ehlers . . 
. Free-living Polycheete (Nereis cultrifera) 5 
. Transverse section of leech—after Bourne F 
. Alimentary system of leech—after Moquin- -Tandon . 7 ‘ 
. Dissection of leech—after Bourne . : 5 ‘ 
. A nephridium of leech—after Bourne . : 
. 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. 
. Actinotrocha or larva of Phoronds—after Masterman 
. Phoronis 
. Diagram of an Ectoproctous "Polyzoon (Plumatella) 
. Interior of Brachiopod shell, showing calcareous support for 
the ‘‘arms ”’—afler Davidson . 
. Pluteus larva of Ophiuroid, with rudiment of adult—after 
Johannes Miiller 
. Star-fish 5 . . 
. Alimentary system of star-fish—after Miiller ‘and Troschel . 
. Diagrammatic cross-section of star-fish arm—after Ludwig . 
. Ventral surface of disc of an oes (Ophiothrix pica 
—after Gegenbaur ji . 
. Apical disc of sea-urchin : . . 
. Dissection of sea-urchin 3 F . 
. Spicules of Holothurians—after Semon . 
. Dissection of Holothurian (Holothuria tubulosa) from the 
ventral surface . 
. Diagrammatic vertical section through disc and base of one 
of the arms of Antedon rosacea—after Milnes Marshall . 
. Stages in development of Echinoderms—after Selenka 
. Appendages of Norway lobster : 
. Section of compound eye of A/ysés vulgaris—after Grenacher 
. Longitudinal section of lobster, showing some of the organs 
. Male reproductive organs of crayfish—after Huxley 
