264 MARTIN P. AVOODWARD. 



origin of the visceral loop by a further concentration of the 

 ganglionic cells. 



7. There is no special concentration of the ganglionic cells 

 just above the future pedal ganglion^ such as Bouvier and 

 Fischer identify as the pleural ganglion, 



8. That in the position of the supporting skeleton of the 

 gills and the possession of a spiral stomach-cEecum Pleuro- 

 tomaria shows signs of a common ancestry with the 

 Cephalopoda. 



9. That Perrier is correct in regarding the single kidney 

 (including* the renal gland) of the Monotocardia as represent- 

 ing both the right and left kidney of the Diotocardia. 



10. That Pleurotomaria may be regarded as a form very 

 closely related to the stock from which the Monotocardia 

 originated. 



July, 1900. 



DESCRIPTION OF PLATES 13—16, 



Illustrating Mr. Martin F. Woodward's paper on "The 

 Anatomy of Pleurotomaria Beyrichii, Hilg.'' 



LUl of Reference Letters. 



(I. a. Anterior aorta. a. h. Aifereiit branchial vessel. a. p. Pedal 

 artery. ^/. /•. /t. Anterior lobe of right kidney. ^. «?. Bile-duct. (i./y. Buccal 

 tjanglion. b. n. Buccal nerve, bn. g. Branchial ganglion, cb. c. Cerebral 

 commissure, ci. _$/-. Cerebral ganglion, c^. /j. Cerebro-pedal connective, cb. 

 pi. Cerebro-pleural conned ive. cr. Crop. cl.l. m. Dorsal longitudinal muscle. 

 d. 111. Depressor muscle, e. b. Efferent branchial vessel, ep. Epipodium. 

 g'., g" . Bight and left gills, g. a. Genital aperture, g. d. Genital duct. g. g. 

 Genital gland. Ii.p. Horny buccal papilla;, i. I. c. Interlaminar connections. 

 i. I. m. Internal longitudinal muscle, int. Intestine, i. r. m. Infra-radular 

 membrane, j. Jaw. k. c. Kidney chamber (right). /. Liver. /. au. Left 

 auricle. /. c. Labial commissure. I. h. Left kidney (|)apillary sac). /. k. a. 

 Left renal aperture. /. /. m. Lateral longitudinal muscle. /. m. Longitu- 



