334 



POLYCHAETA 



only four complete septa, and six pairs of nephridia, which are 

 of large size : th n - fore-gut is eversible. Atlantic and Mediter- 

 ranean. A second and smaller species, A. ecaudata Jnstn., occurs 

 on our southern coasts ; it is readily distinguished by the absence 

 of a " tail," the chaetae and gills being continued to the end of 

 the body. 



Fam. 4. Scalibregmidae. Prostomium ill -marked, fringed 

 with small processes. Parapodia represented by slight papillae ; 

 two bundles of chaetae ; usually cirriform lobes above and below 

 them. Zipobranchius Jeffrey sii M'L has a grub-like body pointed 

 at each end ; forms tubes of mud. Firth of Clyde and elsewhere 

 in North Sea. Sclerocheilus Gr. in old oyster shells. Channel, 

 Mediterranean. Eumenia crassa Oerst. has gills on first six 

 segments. North Sea. Sccdibregma inflata Kthke. has arbor- 

 escent gills on segments 4 to 7. The anterior part of the body 

 is dilated. North Sea. 



Fam. 5. Chlorhaemidae. The family derives its name from 

 the green colour of the blood, due to chlorocruorin. The repre- 

 sentatives are comparatively short worms, with capillary chaetae 

 on all the segments, the limits of which are not evident. The 

 prostomium carries a pair of long grooved yellowish processes, 

 which are perhaps palps, and several green tentacles, acting as 

 " gills," arranged in a transverse series above the mouth (Fig. 134, 

 F, p. 262). The peristomium is achaetous ; the whole " head " can 

 be withdrawn into the body. The chaetae of the anterior seg- 

 ments are especially long, and directed forwards so as to form a 

 " cage " for the head. The body- wall is covered with longer or 

 shorter papillae. Internally, the chief points of interest are the 

 presence of only two septa (Trophonia) or only one septum (Sipho- 

 nostoma), situated somewhere in front of the middle of the body, 

 and forming a great backwardly-directed pouch, which contains 

 a, part of the looped intestine, and the nephridia, of which there 

 axe only two or four. 



Trophonia plumosa MiLll. is about 2 to 4 inches long, 

 yellowish-brown in colour, with a rough skin ; the head is usually 

 retracted. It lives in the mud amongst Laminarian roots down 

 to 50 fathoms. North Atlantic. Siphonostoma (Flabelligera) 

 diplochaitos Otto, has a transparent body -wall, so that the 

 coloured viscera are visible. The skin carries long papillae, 

 which traverse a thick jelly-like envelope secreted by it, in 



