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rather mislcadingly named the anterior ganglion. This structure is apparently peculiar 

 to the shipworms and closely allied forms. The cerebro-visceral connectives give off 

 a few fibres to this ganglion as they pass dorsal to it just before entering the visceral 

 ganglion. 



From the outer side of each of the cerebral ganglia a pallial nerve passes into the 

 mantle, supplying the anterior portion of the mantle and the cephalic hood. From 

 the pedal ganglion several pairs of nerves are given off which innervate the foot. 

 From the anterior ganglion, according to Sigerfoos (1908), nerves are given off to the 

 kidneys and other viscera, and to the osphradia. These last are organs of special 

 sense, peculiar to lamellibranch moUusks, which lie at each side of the visceral ganglion, 

 and are presumed to have the function of testing the water which passes over the gills. 



From the visceral ganglion nerves are given off which pass forward to the large 

 posterior adductor muscle and the anterior part of the mantle, others which innervate 

 the middle part of the mantle, and another large pair of pallial nerves which pass 

 posteriorly into the mantle and finally innervate the muscles of the pallets and the 

 siphons. On either side of the visceral ganglion a branchial nerve is given off which 

 passes into the gills. 



The excretory organs of Teredo are a pair of greatly elongated kidneys {k., fig. 77), 

 which lie dorsal to the pericardium, between it and the anal canal. Each kidney is 

 essentially a long tube which extends forward from the posterior end of the peri- 

 cardium to the region of the posterior adductor muscle, and is then doubled back 

 upon itself and extends posteriorly to a point near its origin, where it empties into the 

 suprabranchial cavity. 



In the region between the posterior adductor muscle and the heart this double 

 tube is elaborated into a many lobed or pouched glandular structure which forms 

 the body of the kidney. The portion of the tube leading forward to this from the 

 pericardial cavity is termed the afferent renal dud, and the opening by which it is 

 connected with the pericardial cavity is known as the renopericardial orifice (r.p.o., 

 fig. 77). The portion of the tube leading posteriorly from the body of the kidney, 

 the efferent renal duct, empties into the suprabranchial cavity through the renal 

 orifice (r.o., fig. 77). 



All these structures are paired. Thus there are two afferent and two efferent 

 ducts which parallel each other, and the orifices mentioned are likewise paired. 



The sexes of Teredo, as our observations indicate, are separate. Sigerfoos (1908) 

 reports finding small hermaphroditic specimens of Bankia gouldi, and suggests that 

 this species may be protandrous (i. e., male when young, later becoming female), as 

 in such cases observed by him the sperms are developed first. Yonge (1926a) has re- 

 cently reviewed the question and from his investigations of Teredo norvegica concludes 

 that this species, at least, is protandrous. Our limited observations on the matter 

 are not contrary to the same view in regard to Teredo navalis; the male specimens are 

 commonly smaller than the females; but definite proof of change of sex is lacking. 



The reproductive organs, the ovaries of the female and the testes of the male, 

 lie dorsal to and at each side of the caecum. During the breeding season the ovaries 

 of the female become greatly enlarged, nearly surrounding the pericardium and the 

 caecum, and the hundreds of separate lobules are densely packed with eggs. 



The eggs, when ripe, are extruded from the genital pore, and in most species of 

 Teredo they enter the gills, where fertilization takes place by the agency of spermatozoa 

 that are taken in with the water of the respiratory current. 



A special brood pouch is developed within the "V" of each gill by a thinning 

 and partial fusion of the filaments, and in this the larvae are retained until they reach 



