ONUPHIS LEPTA. 



All the animals were preserved in situ in their tubes, th ^x portions 



being, in consequence, soft and in poor condition. The^ ,cre removed with 

 difficulty, and no animal was secured entire. One specimen in several pieces, 

 but not fully complete, embraced about one hundred and thirty-eight somites; 

 the most anterior piece, consisting of the head and seventy somites and meas- 

 uring about 70 mm. in length; the somites thus being long. The combined 

 length of the pieces of this specimen is near 150 mm. The greatest width, 

 exclusive of the parapodia, is 2.6 mm. The maximum diameter of the type is 

 3 mm. 



The prostomium is short, cylindrical, rounded distally, and somewhat 

 flattened between the bases of the tentacles. Dorsally there is the usual median 

 longitudinal sulcus from the base of the median tentacle caudad; and ventrally 

 the surface just caudad of the frontal tentacles is concavely depressed. The 

 tentacles are arranged in a circle. The frontal tentacles are small, proportion- 

 ately stout, subcorneal, distally rounded processes separated at the base by 

 about half the basal diameter and strongly diverging from each other distad, 

 each projecting ectoventrad. Each dorsal tentacle consists of the usual stout 

 annulate ceratophore and a long, slenderly subulate, smooth style. The cera- 

 tophore of the anterior paired tentacles is composed typically of four annuli; 

 the style may be as much as four times as long as the ceratophore, reaching to 

 the fourth somite. The posterior paired tentacles reach to the anterior border 

 of the seventh somite. The ceratophore is from a fourth to nearly a half longer, 

 and is decidedly stouter than that of the anterior pair. It is nearly cylindrical, 

 but thicker distally than proximally, and consists typically of eight annuli, of 

 which the most distal is longest. The style becomes very fine distad and is six 

 times, or somewhat more, longer than the ceratophore. The median tentacle 

 reaches to the third somite, being thus considerably shorter than the anterior 

 laterals, and very much shorter than the posterior laterals. The ceratophore 

 is nearly equal in length to that of the anterior paired tentacles, or it may be a 

 little shorter to considerably longer ; but it is much stouter as a rule, though in 

 thickness also varying considerably ; it is somewhat narrowed distad, and con- 

 sists of four articles. The style in the type is nearly four times as long as the 

 ceratophore. The palpi are of moderate size, spherically rounded, and con- 

 tiguous at the middle line. (Plate 45, fig. 1). 



The peristomium is longer and abruptly thicker than the prostomium, and 

 above it rises conspicuously from its anterior to its caudal border. The dorsal 

 surface is smooth. The anterior margin above curves gently forward from the 



