416 TRICOMA AND OTHER NEW NEMATODE GENERA, 



are a little more than half as long as the tail, and are arcuate in 

 the distal half ; their proximal ends are cephaloid by expansion. 

 The substantial accessory pieces are half as long as the spicula, 

 and appear to be situated at right angles to the axis of the body. 

 Hah. — Marine sand, Port Jackson, New South Wales, Australia, 



1890. 



X. Chromagaster, new genus. 



The Chromag asters are slender slow-moving dark-coloured worms 

 inhabiting marine mud and sand. They have a short neck, mitri- 

 form head, tubular pharynx, and very large circular lateral organs, 

 and the sexual organs of both sexes are asymmetrical. The spicula 

 of the males are supported by accessory pieces having a backward- 

 pointing process. 



1. C. NIGRICANS^ n.sp. Female unknown. 



•4 2-3 5- — M 97-7 „ mi i - • ^ i i i ^ i 



■l — -8 -8 — T ^ 4-58 mm. ihe skui IS traversed by about three 



thousand plain transverse striae, and bears hairs throughout, but 

 these latter are conspicuous only near the extremities. The cylin- 

 droid neck terminates in a mitriform head armed with two rows of 

 slender and flexible setse. The posterior row of six setse encircles 

 the head just in front of the large circular lateral organs ; of the 

 setse in this row one seems to be dorsal, one ventral, and the other 

 four submedian. The anterior row is situated half-way between 

 the posterior row and the mouth, and appears to be composed of 

 ten setse arranged in the usual manner, that is, one on each lateral 

 line, and two of unequal size on each submedian line. The largest 

 of these cephalic setse are as long as the head is wide. The pro- 

 jecting mouth is closely surrounded by six small pointed lips. 

 The pharynx is unarmed and tubular and reaches as far back as 

 the anterior border of the lateral organs. These latter are three- 

 fourths as wide as the head and impart to the worm a peculiar 

 appearance. There are no eyes. The tubular oesophagus is only 

 one-third as wide as the neck, but expands in the posterior part 

 to form an elongated bulb two-thirds as wide as the neck. The 

 cardiac collum is distinct and narrow. The thick-walled intestine 

 is three-fourths as wide as the body, and is composed of cells of 

 such a size that about ten side by side make up the circumference. 



