306 DR J. H. ASHWORTH 



The only other Scalibregmid with stronger chsetse in the anterior notopoclia 

 which calls for mention here is that described by Dr ATJGENER * under the name 

 Oncoscolex (Eumenia) heterochastus, in which the first three notopodia bear stronger, 

 bent ehsetse. The description is not as complete as could have been desired, but it 

 affords sufficient evidence the segments are three-ringed, and neuropodial cirri and 

 eyes are absent (or at any rate not mentioned) to indicate that this worm is not, in 

 spite of its stronger chastse, a Sderocheiln*. 



The foregoing considerations show that the genus Sclerocheilus is represented by 

 only two valid species S. minutus Grube and the new species, S. antarcticus, 

 described in the present communication. The diagnosis of the genus Sclerocheilus, 

 as given by GRUBE, and emended by SAINT-JOSEPH, requires some further emenda- 

 tion on the addition of the new species here described. The diagnosis t may be given 

 as follows : 



Sclerocheilus j Grube, 1863, emend. Ashworth. 



GRUBE, Arch. f. Natunj., Jahrg. xxix, Ed. i (1863), p. 50. 

 SAINT-JOSEPH, Ann. Sci. Nut. Zoo!., sur. 7, tome xvii (1894), p. 103. 



Abranchiate sub-fusiform Scalibregmidae ; the prostomium is drawn out into two 

 blunt antero-lateral tentacular processes, and bears, dorsally, eyes which are either 

 separate or are united to form a A-shaped pigmented area ; the peristomium is a 

 single acheetous ring ; the chsetiferous segments (except the first two or three and a 

 few of the most posterior) are subdivided into four annuli ; the two rami of the 

 parapodia are similar in form, and are simple oval elevations arising, in most of the 

 segments, from a glandular raised area of the integument ; stronger, bent cheetse are 

 always present in the first notopodium (in S. fuifarcticus they are present also in the 

 second and third notopodia), but not in the neuropodium ; in the 3rd and all 

 succeeding chsetiferous segments each ramus of the parapodium bears slender 

 capillary chsetae and, anterior to these, furcate chsetee ; the segments of the posterior 

 region possess conical or digitiform neuropodial cirri, and the anal segment or 

 pygidiuni carries four or five (or six) digitiform anal cirri ; a small lateral sense- 

 organ (often recognisable only in thin sections) is present on each parapodium 

 between the notopodium and neuropodium, but nearer the base of the former. 



Type species, S. minutus Grube. 



* Hull. Mux. Uij-niji. Zuol. Harvard, vol. xliii (1906), p. 159. 



t The external features only are considered ; tliere is not sufficient material of 8. antarcticus to enable me to 

 furnish a description nf llie internal organs, or to state if any "f these may be employed as generic characters. 



J inc\-t\p&s, hard ; xeiXos, lip. A name derived from the same roots, but spelt slightly differently Sclerochilus 

 was employ, >d soon afterwards by G. 0. SARS to designate a new genus of Ostracods of the family Cytheridae. See 

 Forhandl. Videiisl,:-M.ik. I'hrMania (1860), 1866, p. 89. 



(ROY. soc. KDIN. TRANS., VOL. L, 418.) 



