208 PROCEEDINGS OF THE ACADEMY OP [1883. 



In the last specimen the rows of 24 hooks in the ninth segment 

 measured 0-08 mm. wide; the rows of 18 hooks of the tenth seg- 

 ment 0-072 mm. wide ; and the i*ows of 14 hoolis of the last segment 

 0'06 mm. wide. The height of the rows corresponding with the 

 length of the hooks was 0-025 mm. 



The intestinal canal of Manayunkia is of extreme simplicity, 

 consisting of a median tube alternately dilated within the segments 

 and contracted in the intervals of the latter, without any other 

 conspicuous division into more distinct portions. The widest 

 expansions are within the fourth to the seventh segment, inclusive, 

 but are also variable in these. Afterwards the intestine becomes 

 narrower to the anus, which opens ventrally in the last segment. 

 The mouth is funnel-like, capacious, and without armature of any 

 kind. Along the intermediate two-thirds of the canal the walls 

 are of a yellowish brown hue. Within the intestine in the seventh 

 segment, and within the terminal portion, active ciliary motion was 

 observed. The intestine, as usual in other annelides, is connected 

 by thin diaphragms to the wall of the body-cavit^y in the intervals 

 of the segments. The intervals are occupied with liquid with 

 multitudes of floating corpuscles. 



The ovaries, with ova in ditferent stages, occupy the fourth to 

 the sixth segment inclusive. Within the lower part of the head, 

 extending thence into the third segment on each side, there is a 

 large elliptical organ, which I have suspected to be the testicle, 

 though I did not examine its structure. 



I was greatly puzzled in the attempt to ascertain the arrange- 

 ment of the vascular system of Manayunkia^ and am in doubt as 

 to the following explanation I give of it. The blood is of a bright 

 green color, and in many positions serves clearly to define the 

 course of the larger vessels. As represented in figure 1, the 

 chief blood-vessels appear to be a large one on each side of the 

 intestinal canal, closely following the course of this so as to seem 

 to form a green coat to it. In each segment of the body the vessel 

 gives off a pair of lateral branches apparently uniting in a loop. 

 In the head the two main vessels leave the sides of the intestine, 

 and after forming a close flexure or a sinus at the base of each 

 lophophore, proceed onward through the interior of the larger pair 

 of tentacles. In viewing the worm in any direction, the two main 

 vessels so constantly appeared at the sides of the intestine, that 

 I at first took them for the walls of the latter itself. The condi- 



