ECHIUROID FAUNA OF NORTH PACIFIC — FISHER 493 



In life it is likely that a normal proboscis can be extended at least a 

 meter in length. 



About 5 mm. posterior to constricted base of proboscis is the com- 

 mon aperture of the two nephridia, and just in front of these and close 

 together are the broken tips of two slender setae (10 mm. long). 

 Upper ends of setae close together and interbasal muscle short. The 

 basilateral muscles are less numerous and stouter than in Maxmillleria 

 lankesteri (Bock, 1942, pi. 4, fig. 1). 



Nephridia two, large. The proximal part, into which the large fan- 

 shaped nephrostome opens, is sharply differentiated from the much 

 larger distal portion in which the eggs are stored and is marked by a 

 few shallow furrows. In the type, the wall of the distal portion is 

 opaque but in the paratype it is translucent, so that the few large con- 

 tained eggs can be seen. The nephridia open by a single median 

 nephridiopore close behind the setae. 



The two anal vesicles are elongate sacs. One side of each is fixed 

 to the wall of the mud-filled cloaca. The free surface of each vesicle 

 is closely covered with fusiform, brown excretory tubules, about 0.5 

 mm. long, from which the terminal funnel has been lost by maceration. 



Alimentary canal : The intestine consists of fragments ruptured 

 from foregut. In the paratype the foregut is sufficiently intact to 

 show its subdivisions. The buccal cavity or anterior part of pharynx 

 is connected with body wall by numerous radiating muscular f renula. 

 Tlie rest of the pharynx is anchored only by the dorsal and ventral 

 mesenteries not shown in figure. The esophagus (proventriculus of 

 Bock) is externally marked by slight constrictions and the very short 

 gizzard by more widely spaced ones. The stomach {C) ends appar- 

 ently at a permanent sharp elbow where there is a sphincter. The 

 presiphonal segment of intestine is short and devoid of a ciliated 

 groove. The mucosa of pharynx, esophagus, and gizzard is thick, 

 marked by longitudinal and circular furrows, but that of gizzard is 

 not so thick as the mucosa of the distal part of esophagus, which is 

 thrown into prominent lappets much as indicated by Bock (1942, pi. 9, 

 fig. 10). The lining of stomach is thinner than that of gizzard and 

 only the longitudinal furrows are present. The cloaca is thin-walled, 

 crowded with mud, and closely attached dorsally by delicate f renula. 

 There are no ventral frenula. In the paratype a short piece of in- 

 testine remains attached to the cloaca. There is no indication of a 

 coecum. 



The vascular system is of the echiurid and not bonelliid type. The 

 neurointestinal vessel, however, arises directly by three roots from the 

 dorsal. The ring vessel appears to be of secondary importance. A 

 bonelliid feature is the position of this plexus at the beginning of the 

 siphon and not at the end of the stomach. 



