658 A. M Verrlll — Tarhellarla, Nemertina, and 



principal character of the group. As in typical Clymenella, there 

 are pennate setoe in the better known species, and perhaps in all, for 

 they may have been accidentally lost in some cases, or else over- 

 looked, owing to their delicacy and fragility. 



Such setJB are known to be present in the following European 

 species: Cli/me7iella {Axiothella) constricta (Clap.); C. (/I.) cir- 

 rifera (Lang.); and C. {A.) lyrocephala (Schm.) from Cape of Good 

 Hope. 



The two northern species, C {A.) prmtermissa (Mg'n.) and C. 

 {A^ polaris (Theel) ai'e not known to have pennate setae, but these 

 may have been accidentally lost or overlooked. 



Clymenella (Axiothella) Somersi, sp. nov. 



A slender species, with eighteen setigerous segments, perhaps 

 more in the adults. The post-abdominal segments are unusually 

 long. 



The head is rather long, with a prominent median lobe having a 

 produced obtuse tip, with a group of orange-brown ocelli on each 

 side below; marginal lobes thin, rather wide, erect, nearly entire, 

 those of the two sides confluent dorsally, with only a shallow median 

 notch. 



Head and buccal segment shorter than the following two seg- 

 ments; 3d to 5th setigerous segments are shorter; 6th is about equal 

 to the 2d; 7th to 9th are elongated; 10th to 15th are very long with 

 the tori at the posterior end. The length of these in a small speci- 

 men is 30 to 38'"™; diameter 3 to 4""'"; the ICth to 18th decrease 

 rapidly in length. Two short preanal segments lack setoe. There is 

 a narrow collar on the 4th setigerous segment and also on the 5th. 



Uncini begin on the 1st setigerous segment, on which three or 

 four stand in a row, in specimens about 50™'" long; four or five in 

 each row on the 2d; six to eight on the 4th; longer rows farther 

 back. 



The caudal segment is cup-shaped with incurved sides and enlai'ged 

 or annulated base; its margin bears about twenty-four slender cirri, 

 alternately longer and shorter, with a distinctly longer one on the 

 median ventral edge. 



The capillary setae of the first three setigerous segments are small, 

 slender, acute, and nearly all are distinctly pennate to the tips, with 

 rather long denticles; on the 4th segment they are partly, and on 

 the 5th mostly, replaced by larger and longer, narrowly limbate, 

 smooth setiB that taper rapidly to acute tips. 



