ZOOL.— Vol. II.] RISEN— OLIGOCHAiTA. 189 



somites. The blood-sinus suddenly leaves the intestine on 

 the dorsal side and assumes the form of an independent 

 blood-vessel, running close to the intestine, and parallel 

 with the dorsal vessel. This supraintestinal vessel exists 

 only in somites XI and XII. It begins near the posterior 

 fourth of XII and extends forwards to the septum separating 

 X/XI. In the posterior of these two somites the supra- 

 intestinal vessel lies entirely free above the intestine except 

 where it is nipped by the septa. In somite XI it is super- 

 posed on the intestine and merely connected by mesenteric 

 tissues with the dorsal vessel in those somites. It is not 

 covered by chloragogen cells; these, however, cover the 

 dorsal vessel, the hearts, and the intestine. The hearts are 

 not much dilated, but appear as tubular vessels of even 

 thickness, without valves. The lateral vessels posterior to 

 the clitellum are covered thickly with chloragogen cells. 

 As in A. Keyesi, each lateral vessel possesses a small 

 diverticle, situated in the centre of the vessel. The present 

 species is more pronounced than in A. Keyesi, being nar- 

 rower and often twisted around the lateral from which it 

 starts. In A. Keyesi two such diverticles are found, but 

 they are smaller and more knob-like. 



Diplocardia communis Garman. 



Diplocardia communis Garman, Bull. 111. Lab. Nat. Hist., Vol. Ill, 188S, 

 p. 47- 

 Definition. — Color, flesh; clitellum dull yellow or flesh. Size, 300 mm. 

 Somites, 123-165. Prostomium divides I by one-half. Dorsal pores, most 

 anterior one X/XI. Spermiducal pores in XIX. Spermathecal pores, three 

 pairs in VII-IX, in line with a-b. Prostate pores in XVIII and XX. Ovi- 

 ducal pores close together in front of and interior to setse a-b. Setae, ventral, 

 a-a slightly larger than b-c, not ornamented; no setae a-b in XIX. Penial 

 setae in XVIII and XX, only slightly curved, smooth, one-third longer than 

 ordinary setae. Spermathecal setae not differentiated. Clitellum saddle- 

 shaped, in XIII-XVIII. Genital zone, copulatory papillae: one pair on 

 XVII, one pair on XX. Copulatory grooves on XVIII-XX, curved towards 

 the ventral median line. With or without a depressed zone. CEsopha- 

 gus, no calciferous folds. Gizzards in V and VI. Sacculated intestine 

 commences in XVII, a low typhlosole from XXIII-XL. Dorsal vessel 

 alternately double and single from VII backwards. Hearts in X-XII. 



