248 ARTHUR E. SHIPLEY. 
brain, I am disposed to think that the main function of the 
tentacles is to create a current, and thus bring food to the 
mouth ; and the chief use of the vascular system is to extend the 
tentacles. 
I am inclined to look for the chief respiratory organ in the 
intestine ; this has very thin and extensive walls, and exposes a 
large surface to the celomic fluid, which in its turn bathes all 
the organs of the body except the brain. A considerable 
volume of water passes through the alimentary canal, enough 
to supply the oxygen required, and this current is maintained 
by the ciliated cells of the groove in the ascending intestine. 
THe MorpHoLocicaL LABORATORY, 
Campripce; August, 1891. 
EXPLANATION OF PLATE IX, 
Illustrating Mr. Arthur E. Shipley’s paper on ‘ Onchne - 
soma Steenstruplli.” 
Fic. 1.—An enlarged view of O. Steenstrupii, with the introvert 
partially retracted. 
Fic. 2.—The same, life size. 
Fic. 3.—A view of the arrangement of the internal organs, shown by opening 
the body-wall along the right side and reflecting the sides. Copied from 
Koren and Danielssen. 
Fic. 4.—Section through a portion of the glandular wall of the nephridium, 
showing the glandular cells and their concretions. 
Fic. 5.—Section through the ascending intestine to show the ciliated 
groove. 
I're. 6.—Section through the skin, parallel with the long axis of the body, 
showing cutis, epidermal glands and their secretions, circular and longitudinal 
muscle layers, and lining peritoneal cells. 
Fic. 7.—Longitudinal section through the posterior end of the body, 
showing origin of single retractor, and the group of peritoneal cells which 
form the testis. 
