424 PROCEEDINGS <>K THE ACADEMY OF [1893. 



muscular lips, of which the dorsal one is the larger and droops down- 

 ward, partially enclosing the ventral lip. Each presents a slight 

 median emargination, but is otherwise entire. The lips and head, as 

 well as the sides of the principal annuli of the body, are provided 

 with a fringe of delicate hairs. Mouth opening nearly circular, be- 

 tween the parted lips. 



The jaws are small and inconspicuous, in adult specimens less than 

 one- twelfth of the width of the head, and of a pale brown or amber 

 color. The rounded base bears three teeth, of which the larger 

 lateral ones are stout, curved, and divergent, while the smaller 

 median one is straight and sharp- pointed. The variations in the jaws 

 involve frequent unsyinmetrical development of the teeth. The 

 dorsal and ventral jaws are similar, and both are fixed opposite to the 

 constriction behind the lips, the teeth being directed inward. 



The straight alimentary canal is strongly sacculated in the second, 

 third and fourth segments, behind which it is narrow, and direct in 

 its course to the anus, which opens on a slight papilla on the dorsal 

 side of the ninth segment. 



The greater part of the body cavity of the fifth and sixth segments 

 is filled with testicular cells in various stages of development; and 

 the glandular thickening of the skin of these segments renders the 

 walls conspicuously opaque. The two pairs of vasa deferentia open 

 into the nearly spherical atrium in the sixth segment. A conspic- 

 uous and broadly pyrifbrm spermatheca opens on the fifth seg- 

 ment. The ovaries and accessory structures occupy the seventh. 

 The anterior nephridia alternate in position, but open to the exterior 

 by paired orifices in segment three. The posterior paired nephridia 

 occupy the space on each side of the intestine in segment eight. 



This species is colorless and more or less translucent ; the first four 

 segments behind the head are remarkably clear and translucent, but 

 behind this the body walls are rather opaque and the position of the 

 internal organs obscured. The alimentary canal is throughout darkly 

 colored, except within the head. 



Blood very pale red. 



Length of mature individuals (> mm. 



Maximum breadth 1\3 " 



Width of jaws- -06 " 



Diameter of acetabulum -(i " 



