212 



EXPLANATION OF FIGURE 77 



1. Stereogram of Teredo navalis, anterior part, including the visceral mass, nearlv 

 all of the left half of the body ha\'ing been removed to disclose structures lying in or 

 near the sagittal plane. The anterior end of the animal is to the reader's left. The left 

 half of the stomach, removed in this figure, is shown in figure 78, 1. Animals killed in 

 alcohol ha\ e the foot completeh- retracted and all the drawings ha\'e been made with 

 it in this condition. X7. 



2-5. Diagrammatic cross-sections at the levels indicated on 1. Anterior aspect. 



a. 



a.a. 



a.ao. 



a.b.v. 



a.c. 



a.l. 

 a.r.d. 

 a.st. 

 an. 



CM. 



ex. 



CO. 



c.r. 



C.I. 



c.l.i. 

 d.a. 



d.D. 



d.f. 



e.r.d. 



/. 



'.D. 



g.o. 

 g.s. 



S-t. 



ih.c. 



in. 

 k. 



Anus. /. 



Anterior adductor muscle of the valves. I.e. 



Anterior aorta, homologous with the an- 

 terior aorta of other lamellibranchs, 



though running posteriorly in Teredo. 

 Afferent branchial vein, paired anteriorly, 



but single in the region of the gills. in. 



Anal canal, a forward extension of the ma. 



suprabranchial cavity. od. 



Anterior liver. oe. 



Afferent renal duct (paired). ov. 



Anterior part of stomach. 

 Auricle of the heart. The left one is 



shown cut olif close to the ventricle. />. 



Branchial groove. One lies along each p.a. 



ventral edge of the gills, continuing p.ao. 



forward on the side of the body to 



the labial palps. 

 Caecum of the stomach. In figure 1 the p.ar. 



left wall is remo\'ed, except from the 



posterior fourth. 

 Caecal artery. pe. 



Cerebral commissure, connecting the 



cerebral ganglia, which are widely 



separated. 

 Ciliated strip on the mantle. p.g. 



Caecal orifice. p.h.o. 



Ciliated ridge. p.l. 



Caecal typhlosole. p.st. 



Coiled typhlosole of the intestine. r.o. 



Dorsal articulation, or pivotal knob, of r.p.o. 



the shell. i. 



Duct of the gland of Deshayes. 

 Dorsal pallial fold. 



Efferent renal duct (paired) s.a. 



Foot, 



Gill. sh.c. 



Gland of Deshayes in the gill lamellae. 



(Discovered and named bv Sigerfoos, s.c.s. 



1908.) 

 Gastro-intestinal typhlosole. st. 



Right genital orifice. v. 



Gastric shield. Only a small part of the 



right edge shows in figure 1. 

 Gastric typhlosole. v. a. 



Intestine. The arrows point toward the 



anus. v.g. 



Infrabranchial cavity. The arrow indi- v.h.o. 



cates the direction of the flow of water. 

 Integument of the visceral mass. v.!. 



Kidney, the tubular, spongy part of the 



excretorv system. 



Ligament of the shell. 



Lateral canal. These are lateral, anterior 

 extensions of the suprabranchial cav- 

 ity, communicating with the infra- 

 branchial cavity through the anterior 

 gills (see fig. 76). 



Mouth. 



Mantle. 



Right oviduct. 



Oesophagus. 



Ovary. In male specimens the testes are 

 similar in extent and relations (see 

 fig. 79, 2-4). 



Pylorus. 



Posterior adductor muscle of the valves. 



Posterior aorta, homologous with the 

 posterior aorta of other lamellibranchs, 

 though running anteriorly in Teredo. 



Pallial artery, a continuation of the pos- 

 terior aorta after it has looped over 

 the posterior adductor muscle. 



Pericardium. Posteriorly it bifurcates, 

 one auricle of the heart extending into 

 each ramus and one atlferent renal duct 

 opening from each. 



Pedal ganglia. The two arc fused. 



Posterior hepatic orifice. 



Posterior liver. 



Posterior, pyloric region of the stomach. 



Right renal orifice. 



Right reno-pericardial orifice. 



Septum, separating regions that are prob- 

 ably homologous with the pedal and 

 venous sinuses. 



Supraoesophageal artery, a branch of the 

 posterior aorta. 



Suprabranchial cavity. The arrow indi- 

 cates the direction of the flow of water. 



Sac of the crystalline style. Figure 1 

 shows the distal end from the inside. 



Stomach. 



Ventricle of the heart. The arrows at its 

 anterior end indicate the direction of 

 the flow of blood. 



Ventral articulation, or pivotal knob, of 

 the shell. 



Visceral ganglia. 



Ventral hepatic orifice. There are four of 

 these, as shown in figure 1. 



Ventral liver. 



