EXPLANATION OF THE LETTERING. 



br. Branchial aperture. 



l>r. s. Branchial sac. 



b. t. Branchial tubercle. 



en. Endostyle. 



i. Intestine. 



m. Mantle. 



mo. Month. 



n.g. Nerve-ganglion. 



ce. (Esophagus. 



od. Oviduct. 



o. /. Oral lamina. 



t. Test, 



t. c. Tentacular collar. 



tn. Tentacles. 



ts. Testis. 



v. Ovarv. 



/ 



v. t. Blood-vessels leading to test. 



