MOYANUS EXPLORANS. 453 



treme anterior end to the end of the thorax is only 25 mm. The greatest width 

 is 4 mm., this being at the anterior end, from where the body is cyhndrical and 

 of essentially uniform diameter to the end of the setigerous region, caudad of 

 which it is much, though gradually, narrowed to just proximad of the extreme 

 caudal end, which is expanded in a subcampanulate manner. The body of the 

 type in the middle and posterior region is conspicuously compressed dorso- 

 ventrally. 



The prostomium above is prolonged directly forwards into a remarkable 

 proboscis-like process, which in the type is about 7 mm. long, and if laid back 

 from the base would reach about to the eighth somite. It is flattened dorso- 

 ventrally and is of uniform width to the distal end, which is somewhat convexly 

 rounded. Along each lateral edge is a series of crenations, or blunt rounded 

 lobes, from between which a furrow extends a short distance mesad both above 

 and below but quickly fades out, leaving the middle upper and lower surfaces 

 nearly smooth. These cross-furrows give the process in part a segmented 

 appearance. Ventrad of the lobe the prostomium presents a very much shorter 

 tentaculiferous lobe, scarcely more than one third as long as the upper one. 

 This has a broad, slightly convex, ventral surface and in outline, as seen from 

 below, is subtrapeziform, with the distal margin slightly concave. On each 

 side of the ventral surface, beginning near the median line, a stout transverse 

 lobe is set ofT by deep sulci, and has its ectal tip projecting freely at the side like 

 the tip of an ordinary tentacle, the free portion, however, being short. The 

 other tentacles are attached along the lateral edges of the lobe. On each side 

 of the lobe and toward the anterior end is attached a basally stout, subconically 

 narrowed tentacle which projects forwards, and in length is scarcely, or not at 

 all in excess of the width of the lobe across its anterior end. Caudad of this 

 tentacle and in hne with it on each side are two much shorter, distally rounded 

 tentacles, or tentacular lobes, which are distally rounded, and of which the more 

 caudal on one side is shghtly divided, the corresponding one of the opposite 

 side being lost. 



There are four pairs of branchiae. The four of each group are inserted 

 contiguously. They differ but slightly in length and extend distad to near 

 the middle of the upper lobe, or rostrum, of the prostomium. All are gradually 

 and uniformly attenuated from thick bases to pointed tips. Distally they are 

 subcyhndric, but proximally they are flattened and show a median longitudinal 

 furrow. They are smooth throughout, showing no traces of pinnate branches 

 such as occur in Isolda. 



