Haddon — Oil Generatke and Urinary Ducts of Chitons. 237 



EXPLANATION OF PLATES X. AND XL 



All the figures are from spirit-preserved specimens of Chiton 

 (Tracliydermon) ruber (Limi.), and are drawn to the same scale, i.e. 

 about 28 diameters. 



Ao., aorta, au., auricle, h. a., branchial artery, br., gill. b. v., 

 branchial vein, c, commissure of pedal nerve cord. e. d., external 

 duct of the body of the kidney, ft., foot, gl, fenestral gland, int., 

 intestine, k. b., body of the kidney. I. /., longitudinal fold of the 

 mantle. Z.w.c, lateral nerve cord, m., mantle. ocZ., oviduct, opiig., 

 opening of the kidney into the. pericardium, ov., ovary, o. ov., 

 external orifice of oviduct, jyc, pericardium, ^j. d., pericardial or recur- 

 rent duct of the kidney. ;j. n. c, pedal nerve cord. 2^. v., pedal blood- 

 vessel, pv. c, perivisceral cavity, r., rectum, r.p. d., recurved portion 

 of pericardial duct of the kidney, v., cavity caused by the decalcifi- 

 cation of an anterior sutural lamina of the succeeding valve. 



Plate X., Fig. 1. — Transverse section of body in region of the ovi- 

 duct, giving a longitudinal section of the latter (combined from three 

 consecutive sections). 



Figs. 2, 3, and 4. — Transverse sections of another specimen at the 

 posterior end of the body, in the region of the " fenestral gland," of 

 which 2 is the most anterier, and 3 the most posterior. Notice the 

 complexity of the infoldings of the gland ; the scattered groups of poly- 

 gons are transverse sections of other portions of the gland. Li Fig. 2 

 the auricles {au) are seen ; in Fig. 3 they fuse together ; and in Fig. 4 

 their posterior wall is just seen. The pedal nerve cords are seen to 

 gradually dwindle away posteriorly. 



Plate XL, Figs. 5, 6, 7. — Portion of transverse sections in region of 

 the kidney-ducts of same specimen as Fig. 1, showing the opening of 

 the pericardial duct into the pericardium, and the external duct of the 

 kidney-body. 



Fig. 8. — Diagram to show the relations of the urinary ducts. 



SCIENC. PROC. E.D.S.— YOL. IV., PART V. 



