EXPLANATION OF PLATES 



PLATES 21 ANT) 22 



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

 mass, nearly all of the left half of the body having 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 plate 23, figure 6. Animals killed in alcohol have the foot completely 

 retracted and all the drawings have been made with it in this condition. Figure 

 1 and figures 6 to 9 are stereograms and all are drawn to the same magnification, 

 about 7 diameters. 



Figs. 2—5. Diagramatic cross-sections at the levels indicated on figure 1. 

 Anterior nspect. 



Q- 

 Q.D. 



Anus. 



Anterior adductor muscle of the valves. 



Anterior aorta, homologous with the 



anterior aorta of other lamellibranclis, 



though running posteriorly in T>n-!<- 

 Afferent branchial vein, paired anter- 



iorlv, but single in the region of the 



gills. 

 Anal canal, a forward extension of the 



suprabranchial cavity. 

 Anterior liver. 



Afferent renal duct (paired). 

 Anterior part of stomach. 

 Auricle of the heart. The left one is 



shown cut off close to the ventricle. 

 Branchial groove. One lies along each 



ventral edge of the gills, continuing 



forward on the side of the body to the 



labial palps. 

 Caecum of the stomach. In figure 1 the 



left wall is removed, except from the 



posterior fourth. 

 Caecal artery. 

 Cerebral commissure, connecting the 



cerebral ganglia, which are widely 



Ciliated strip on the mantle. 



Caecal orifice. 



Ciliated ridge. 



Caecal typhlosole. 



Coiled typhlosole of the intestine. 



Dorsal articulation, or pivotal knob, of 



the shell. 

 Duct of the gland of Deshayes. 

 Dorsal pallial fold. 

 Efferent renal duct (paired). 

 Foot. 

 Gill. 

 Gland of Deshayes in the gill lamellae. 



(Discovered and named bv Sigerfoos. 



1908.) 

 Gastro-intestma! typhlosole. 

 Right genital orifice. 

 Gastric shield. Only a small part of the 



right edge shows ' 

 Gastric tvphlosole. 

 Intestine. T* 



i figun 



point toward the 



Infrabranchial cavity. The arrow indi- 

 cates the direction of the flow of water. 



Integument of the visceral mass. 



Kidney, the tubular, spongy part of the 

 excretory system. 



Ligament of the shell. 



Lateral canal. These are later, anterior 

 extensions of the suprabranchial cav- 

 ity, communicating with the infra- 

 branchial cavity through the anterior 

 gills (see pi. 24, fig. 9). 



Mouth. 



Mantle. 



Right oviduct. 



< >esophagus. 



Ovary. In male specimens the testes are 

 similar in extent and relations (see 

 pi. 24, figs. 11-13). 



Pylorus. 



Posterior adductor muscle of the v;ilv.- 



Posterior aorta, homologous with the 

 posterior aorta of other lamelli- 

 branchs, 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 afferent renal 

 duct opening from each. 



Pedal ganglia. The two are fused. 



Posterior hepatic orifice. 



Posterior liver. 



Posterior, pyloric region of the stomach. 



Right renal orifice. 



Right reno-pericardial orifice. 



Septum, separating regions that are 

 probably 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 ol 

 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. 



[470] 



