BV W. A. IIASWELL. 



95 



The prostoiiiium is nearly twice as Ijioad as Jong, with four very small eyes. 

 The median tentacle is about thrice the length of the ijrostomium. with about 25 

 joints; the lateral a little shorter, with about 17 joints. The palpi are ovate, veiy 

 little narrower at the apex, with the inner edges, in close contact with one another 

 at the base Init not fused, diverging very slightly distally. 



The dorsal peristomial tentacle is nearly as long as the median, with about 

 18 joints; the ventral a little shorter. 



The parapodia are relatively long; nearly half the breadth of the body in 

 length, and in general outline resemble those of ,S'. pectinans. Each has about 

 8-10 compound setae. These (Plate x., figs. 8 and 9) are all of the same type, 

 the only ditt'erence between them being a gradual reduction in length of the falx 

 from the dorsal to the ventral side; all are bidentate with a small secondary 

 tooth and a row of tine cilia along the cutting edge. A simple seta ( Plate x., 

 fig. 10) lies on the dorsal side of the compound seta in a variable number of the 

 most posterior segments. It differs from the simple setae of S. variegata and 

 S. pectinans in being truncate. A shorter, simple, pointed seta lies on the ven- 

 tral side in the last two or three segments. There is sometimes a single aciculum 

 in each parapodium, sometimes two or three: they are sharply bent forwards at 

 the ends. (Plate x., figs. 11-14. ) 



The dorsal cirri are long and thick, the first being the longest, with about 28 

 segments. The rest are alternately longer and shorter, the longer (about 25 

 joints) longer than the breadth of the body, the shorter (about 17 joints) about 

 e(iual to it. The ventral cirri scarcely reach as far as the ends of the parapodia. 

 The anal cirri have about 16 joints. There is a narrow median process between 

 them as in S. pectinans. 



The pharynx is red in colour. When the proboscis is fully drawn back it is 

 long and narrow, extending from the fourth segment, in which the tooth is situ- 

 ated, to tlie thirteenth. The proventriculus is relatively short, extending through 

 only about four to six segments. 



Syllis tricncata has been found in Port Stephens as well as Port .Jackson. 



Many specimens of S. truncata bear either one or two white spots on the 

 dorsal surface over the proventriculus or its junction with the intestine. When 

 two are present they may occur on the 16th and 17th or on the 17th and 18th 

 segments ; when one only occurs it is usually found on the 18th segment . These 

 white bodies lie in the substance of the dorsal body-wall between the ejiidermis 

 and the muscular layers, and extend across a considerable part of the breadth 

 of the segment. Contained in each are a large number of rounded masses of an 

 average diameter of about .05 mm., each made up of innumerable minute cor- 

 puscles of an approximate diameter of 0.002 mm. 



That these bodies are encysted Sporozoa appears to admit of little doubt . 

 The constancy of their position would appear to be accounted for by the position 

 of the ventriculus and caeca^ — the walls of the latter being comparatively tliin and 

 easily traversed by the trophozoite in its migration outwards from the lumen of 

 the alimentary canal. 



In liis description of the Polycliaeta of the Canaries Langerlians (35) gives 

 an account of a species of Ti/posi/llis, which he calls T. pulvinata, characterised 

 by the presence of cushion-like elevations of the dorsal surface of the 18th, 19th, 

 and 20th segments. There can be little doubt that in this species the swellings 

 are due to the same cause as in T. truncata. T. pulvinata is described as having 



