172 TRYPANOSYLLIS ZEBRA. 



diagnostic coloured figure of the head and anterior region, and shows the true structure 

 of the pharynx in extrusion, with its anterior circle of rounded papillae and its posterior 

 of chitinous, hook-like processes. He describes the feet as cylindrical and trilabiate, but 

 his figures of these and of the bristles need improvement. He pointed out the caeca of 

 the intestine, which he thought comparable with those of Aphroditaceans, but it dis- 

 appeared in the stolons. Its blood was of a fine pale rose colour. 



Marenzeller (1864) states that the number of the papillae of the proboscis is twelve, 

 and he thinks that it differs from the Tryjpano syllis Krolmi of Claparede — amongst other 

 reasons because that form has only ten teeth (papillae). 



Langerhans (1879) mentions an additional pair of eye-specks on the ventral surface, 

 and a median process between the anal cirri. He also describes and figures the intestinal 

 caeca anteriorly. In the last six to twelve segments is a simple bristle. 



Marion and Bobretzky (1875) found at Marseilles, in February, buds of a yellowish 

 and rose colour, 20 mm. long. Their dorsal cirri were more cylindrical and shorter 

 than that of the nurse-stock. Two large eyes occurred on the head with two lateral 

 antennae and two minute palps. Swimming-bristles were present. The nurse-stock 

 regenerated its posterior segments. These buds have the form of Tetraglene. 



De St. Joseph (1886) gives a careful account of this species, mentioning that in the 

 terminal segments are simple birostrate bristles. He describes ten soft papillae at the 

 end of the proboscis, followed by ten corneous ones, and a single large conical tooth. 

 The intestine has for some distance lateral caeca, He adds further information as to its 

 reproduction by budding either by male or female stolons which have the form of 

 Tetraglene, Grube, and shows that such are not to be confounded with Chxtosyllis, Mgrn., 

 as Langerhans does, since they differ in the configuration of the head, which is devoid of 

 tentacles. Besides this type of head in the stolons of the Syllideans, there are (1) the 

 form seen in Syllis arnica, De Quatref. ; (2) the form of Mela, Johnston; (3) the form of 

 Chdetosyllis, Mgrn.; (4) the form of Sacconereis ; and (5) the form of Polybostrichus. The 

 male buds of Trypano syllis zebra are reddish-brown, the dorsal cirri brownish- violet, with 

 14 — 16 articulations, and with two kinds of bristles, viz. compound as in the nurse-stock, 

 and from the third segment a superior fascicle of swimming-bristles. Moreover the feet 

 are long. The head shows a deep median cleft and carries on each side a pair of very large 

 eyes, the inferior (ventral) being usually the larger, and having in addition only the dorsal 

 and ventral cirri of an ordinary segment. It thus corresponds with Grrube's Tetraglene. 

 The body is filled with sperms. The female stolon has also four large eyes, but the head 

 is less deeply incised in front. The dorsal cirri are nearly of equal size and have sixteen 

 articulations. The feet are much shorter than in the male, and the entire body is 

 distended with eggs, the intestine, as in the male, being rudimentary. It also has dorsal 

 swimming-bristles from the third segment. After the separation of the buds from the 

 nurse-stock, regeneration of the posterior segments occurs in the latter with the 

 development of caudal cirri. 



The Syllis maculosa of M. Edwards 1 does not appear to diverge much from this 

 species, though the author observes that the tentacular cirri are absent, and shows the 



1 c 



Regne Anim. lllust./ pi. xv, fig. 1. 



