686 DAVID HILT TENNENT. 
DESCRIPTION OF PLATES 39—42, 
Illustrating the paper by Mr. David Hilt Tennent on “A 
Study of the Life History of Bucephalus haimeanus, 
a Parasite of the Oyster.” 
Abbreviations. 
ain, Anterior lateral nerve. dp. Bladder-like portion of middle piece. 
br. Brain. cere. Cercaria. c.sac. Contractile sac. ctg. Cystogenous gland. 
clgo. Cystogenous organ. cst. Cyst. cé/. Cavity in middle portion of tail. 
cu. Cuticle. ecw. Wall of yolk cells. d. Duct. da. Anterior duct. de. 
Digestive cell. dg. Sperm duct. dp. Dorsal pore. dp’. Posterior duct. 
dve. Dorso-ventral canal. ed. Hjaculatory duct. ep. Epithelial cells. 
exp. Kxcretory pore. jl. Flame cell. rd. Formation cells of refractive 
bodies. g.a, Genital atrium. g.d. Germ ball. g.c. Germ cell. gi.c. Gland 
cell (sunken epithelial cell). gp. Genital pore. gpw. Glandular muscular 
fold. gril, Granular layer. gt. Gut. g.¢. Germ tube. iv. Three-lipped 
invagination, 4&/. Keimlager. Zc. Laurer’s canal. JZcp. External opening 
of Laurer’s canal. dm. Longitudinal muscles. /.m,f. Longitudinal muscle 
fibres. dz. Lateral nerve. dum. Lumen. Js. Left testis. mb. Muscle band. 
me. Constrictor muscles surrounding cystogenous organ. mp. Mucous plug. 
myb. Myoblast. 2. Nucleus in membrane. ze. Nerve cell. zdc. Nuclei 
gut cells. z.s, Neural sheath. aye. Nucleus yolk cell. o.dr. Oil droplets. 
as. (Usophagus, om. Oblique muscles. o.w¢. Opening of uterus to atrium, 
ovd. Oviduct. ovy. Ovary. oyst. Oyster tissue. yp. Penis. par. Paren- 
chyma. par.n. Parenchyma nuclei. pd. Polar bodies. pA. Pharynx. ppr. 
Protuplasmic processes. ps. Penis sheath. pt. Disintegrated material be- 
tween wall of germ tube and tissues of host. 76. Refractive bodies. rdm. 
Radial muscles. reé.p. Reticulated parenchyma. 7m. Circular muscles. 
rm’, luner layer circular muscles. .mf. Circular muscle fibres. ps. Rudi- 
ment of penis sheath. és. Right testis. sc. Sub-cuticula. sd. Sucking 
disc. sh. Sheil glands. shgd. Shell glands. sm. Sphincter muscles. sp. 
Spines. sv. Seminal receptacle. sv. Seminal vesicle. 7c. Canal to tail. 
dl. Tail. dr. Rudiment of tail. ¢s. Testis. wt. Uterus. uw. Uterine wall, 
ve. Vacuole. vd. Vas deferens. vit, Vitelline ducts. v7¢/, Vitellaria. 
vp. Ventral pore. we. Wall of cyst. w.g.t. Wall of germ tube. wph. Wall 
of pharynx. wp. Excretory pore. .vas. Water vascular. ygr. Yolk 
granules. 
