AND HABITS OF THE AMMOCHARIDA. 259 
EXPLANATION OF THE PLATES. 
Reference Letters. 
@., anterior extremity. @.p., anal pores. 0., brain. 6.¢., branchial tentacles. 
b.w., body-walls. ¢., collar. ch., bristle-bearing process. c.l., cephalic 
lobe or crescent. ¢.m., circular muscles. ¢.p., cephalic pore. .#., conical 
tip of tube. d.c., intestine. ¢., eye-spot. @., esophagus. .c., epithelial 
canal. f.s., fragment of stone or shell. fv., flap-valve. h.b., epidermal 
band. h.c., high cells of Lippen-organ. 7, under-lip. J.c., shorter cells 
ot Lippen-organ. 1./., lateral lobe. ¢.m., longitudinal muscles. /.0., Lippen- 
organ. J.r., upper-lip. m., mouth. m.t., membranous tube. p., posterior 
extremity. s., sete. s.¢., stony covering of tube. sp., septum. s.v., 
sphincter valve. 7, torus. 7¢g., thread-gland. ¢.p., thoracic pouch. 
t.v., “thoracic” septal valve. w., uncini. v.a., thin ventral “ thoracic ” 
area. 
Prats 23. 
Fig. 1. Diagrammatic section of Ammochares, illustrating method of forming 
the imbricated tube. 
2. Ammochares filiformis. Cephalic segment viewed from above, showing 
the internal lobes (¢./. & 7.) as they would appear during life. 
This is a restoration of fig. 3. 
3. Ammochares filiformis. Cephalic segment viewed from above (von 
Drasche), showing the ‘“ Lippen-organ ” (/.0.) and mouth (m.), which 
are frequently visible after death owing to contraction of the three 
lobes. 
4. Uncini of Ammochares :— 
a’. Ammochares assimilis, Sars (4. Pl. xii.). 
be 5 ottonis, Grube (5. Pl. xv.) 
che 5p Susiformis, D. Chiaje (29. Pl. xxii.). 
d’. Uncinus of Mitraria, Metschnikoff (7. Pl. xviii.). 
5. Diagrammatic vertical section of a posterior segment of Ammochares, 
showing the action of the septal valves (fv. & s.v.). 
6. Dorsal view of second “‘ abdominal” segment of Ammochares, showing 
the zigzag epithelial canal (¢.c.) in the lateral bows ; also (in dotted 
outline) the form and position of the thread-glands. 
PuatE 24. 
Fig. 7. Vertical longitudinal section of anterior extremity through centre 
line of Owenia filiformis (English), showing, ventrally the ‘‘ Lippen- 
organ” (/.0.) in sitw when at rest; and dorsally the cephalic lobe, 
with indication of cephalic (prostomial) pore (¢.p.). X45. (From 
a thick section.) 
