( 405 ) 



XIV. — On a New Species of Sclerocheilus, with a Revision of the Genus. By J. H. 

 Ashworth. D.Sc, Lecturer in Invertebrate Zoology in the University of 

 Edinburgh.* 



(MS. received May 4, 1914. Read May 25, 1914. Issued separately July 2, 1915.) 



[Plate XXXVIL] 

 CONTENTS. 



PAGE 



Description of the Specimen collected in Scotia Bay, 



South Orkneys 405 



Systematic Position of the Specimen from Scotia Bay 409 

 Observations on Sclerocheilus minutus Grube . . 410 

 Observations on Sclerocheilus pacificus J. P. Moore . 414 

 Sclerocheilus cxcus Saint- Joseph . . . .415 



PAGE 



Observations on a Specimen of " Eumenia oculata " 415 



Sclerocheilus Grube, emend. . 418 



Sclerocheilus minutus Grube .... 419 



Sclerocheilus antarcticus n. sp. . . . .421 



Description of Plate 422 



The Polychsete family Scalibregmidse comprises seven genera, the limits and inter- 

 relationships of which are, however, still imperfectly known. The present paper 

 results from a detailed study of one of these genera, a new species of which is de- 

 scribed, chiefly from a specimen collected in Scotia Bay, South Orkneys, and entrusted 

 to me for examination by Dr W. S. Bruce. 



Description of the Specimen collected in Scotia Bay, South Orkneys. 



This specimen, the only Scalibregmid found by the Scottish National Antarctic 

 Expedition, was dredged on a stony bottom in ten fathoms at Station 325, in Scotia 

 Bay, South Orkneys (lat. 60° 43' 42" S. ; long. 44° 38' 33" W.), in August 1903. 



The worm, which is yellowish brown in colour (in alcohol), is 19 mm. long. The 

 anterior portion is broad; the maximum breadth, 3 mm., is reached about the level 

 of the 1 0th segment ; from this region the worm tapers gradually to the anal seg- 

 ment. The dorsal surface of the worm is strongly convex ; the ventral surface is 

 flattened, and there is a well-marked depression which extends along the mid-ventral 

 line from the 2nd chsetiferous segment almost to the anus. 



The prostomium is drawn out at each side into a stout, bluntly conical process 

 (PI. XXXVII, fig. l). On the middle region of the dorsal surface of the prostomium 

 there is a A-shaped area of dark-brown pigment representing the eyes. The point of 

 the A is median, and is situated near the centre of the prostomium ; each limb of this 

 pigmented area passes obliquely backwards and down the side of the prostomium. 



The peristomium consists of a single, achsetous ring, which is incomplete ven- 

 trally, where it forms the antero-lateral borders of the mouth (figs. 1, 2). 



* A grant in aid of the expenses incurred during this research has been received from the Earl of Moray Endow- 

 ment of the University of Edinburgh. The cost of the woodcuts and of the reproduction of the figures on the plate 

 has been defrayed by the Carnegie Trust for the Universities of Scotland. 



TRANS. ROY. SOC. EDIN., VOL. L, PART II (NO. 14). 57 



