Chsetopterus Variopedatus. 527 



The wide, horizontal portion of nearly every tube bears one or more 

 of these strips inserted between the edges of a thicker laminated 

 wall. This was true even in the smallest specimens, No. 2 and !No. 

 4, which I mentioned on page 525. The diameter of their tubes was 

 twice enlarged while they were thirty-eight and thirty-two milli- 

 meters long, respectiveh', and before they constructed the next linear 

 enlargement. 



The outer surface of the tubes is evei*ywhere coated with sand, 

 excepting about the terminal portions that protrude above the sand 

 flats in which they are imbedded. These terminal portions have one 

 or more aimulations that give them the appearance of being formed 

 of rings that diminish regiilarly in size upwards, so that the bases 

 of the smaller rings are overlapped by the top of the ring next below. 

 Each ring represents the successive height of the orifice, though not 

 its diameter, for they are split from time to time as I have just 

 shown. They are molded, like the other portions of the tube, by 

 the ventral lip of the buccal funnel, and the length of each ring- 

 represents the height to which the lip was extended when it was 

 formed. The rings are, at first, very thin and transparent, but they 

 become laminated by successive additions of mucus to their inner 

 walls. The laminte of which they are the free ends may be separated 

 with ease from those next below. 



Summary. 



The species of Chsetopterus which is found at Beaufort, North 

 Carolina, is Chcetopterus variopedatus instead of Chcetopterus perga- 

 mentaceus of various authors. 



The cowl-like structure which is on the dorsal side of the thirteenth 

 somite of the body is an accessory feeding-organ. It is not a "dorsal 

 sucker" as was claimed by Laffuie. 



The dorsal diverticulum of the oesophagus is provided with gland- 

 ular walls. It is of the same length and diameter as the food-uiasses. 

 It is possible that the food collects in it and is formed into little 

 masses such as are found throughout the intestine. 

 . The intestine is provided, along its dorsal side, v/ith a ciliated 

 groove that extends backward from the ciliated portion to the posterior 



