ANATOMY OF STTTROA ROSTRATA. 3 



sentation of tlic same. I gciienilly rmiiid three eggs or young worms in the 

 capsule. 



The worms appear full}- developed in July and August, at which time I 

 found mature specimens. In May only immature ones were found, hut as some 

 of those were quite small it is likely that the worms remain mature for a long 

 period, and that perhaps tlie projicr breeding season is during the winter luonths. 



In size and fonn Suiroa roMruta nuudi resembles Rhynchelnm limoseUa. Iloirm. 

 Mature specimen reaidi a length of three incdies ami a width of one -eighth of aa 

 inch, hut generally are considerably smaller. The form is also similar to that of 

 the above worm. The body is round oi- quadilateral ; in many specinuMis the sides 

 are even concave (Fig. 3). The })osterior part of the body is again vei-y much flat- 

 tened out. quite transparent, and so brittle that care is necessary to get any entire 

 specimen. 



The anterior part of the worm, or the cephalic lobe proper, is elongated and 

 filiform, its length exceeding the width of the body. This characteristic is 

 also found in Rhynchelmis Umosella, and indeed so similar are the two worms exte- 

 riorly that one may easily be mistaken for the other. Fig. 1 represents a Sutroa, 

 nat. size; Fig. 2, the anterior portion of the body; and Fig. 3, a transverse section 

 of a quadilateral specimen. 



Vascular Systein. — The dorsal vessel (Figs. 4 and 5, v. d.) is pulsating. The 

 ventral vessel (Fig. 4, v. v.) is not pulsating. In the figures the pulsating vessel is 

 represented red, the non-pulsating one as blue. The ventral and dorsal primary 

 vessels ai-e connected in the cephalic lobe, where at the apex one vessel connects 

 directly with the other (Fig. 4, I). Between this cephalic plexus and segment 

 XIII no direct connection exists between the two primary vessels. But from 

 segment XIII toward the posterior end of the body, we find in everv one 

 a secondary gastric vessel which undoubtedly connects the dorsal and ventral pri- 

 mary trunks. 



The dorsal primary vessel (Figs. 4 and '5, d. v.) is entire, not forked, as is 

 the case in the other genera of Lumhriculina. In every segment it emits secondary 

 vessels, which are of two kinds, gastric and jm'igastric. The [lerigastric vessels 

 occur in all the segments of the body; the gastric vessels only in the posterior, 

 beginning with segment YIII. 



In each of the six anterioi' segments we find only one pair of perigastric ves- 

 sels, but each vessel shows a distinct forking, less so in segment I, but more dis- 



