Gutty Marine Laboratory, St. Andrews. 179 



in length to the 7th or 8th, and then gradually diminish 

 posteriorly. Their structure corresponds with that in 

 S. spinvlosa. The lateral region has the segment-ridges and 

 the lamellae for the hooks, the latter posteriorly projecting 

 outward as long cuneiform processes. The dorsal surface 

 is marked by close transverse striae and an ovoid area 

 about the 6th and 7th branchiae. Vcntrally the groove at 

 the same level has a similar depressed ovoid area, and the 

 caudal tube lies in the groove posteriorly, whilst anteriorly 

 the groove commences behind the first (or thoracic) region. 

 Behind the fragmentary segment just described is the first 

 region of the body proper (thoracic auctorum) consisting 

 of three segments, each with a dorsal branchia and a 

 lateral setigi rous lamella, which increases in length and 

 breadth from the first to the third. The first is least 

 and has slightly smaller oar-shaped bristles (7 in number), 

 the pointed translucent tips of which are only a little fringed 

 and thus differ from those of SabeUaria spimdosa with their 

 deep fissures. The second has a longer lamella than the 

 first and a few bristles more, and the third exceeds both in 

 these respects, and the bristles often show asymmetrical tips. 

 The shafts of all these oar-shaped bristles are remarkably 

 long, penetrating deeply into the tissues, and they also 

 appear to be flat. Between each, as a rule, is a slender 

 finely spinous form, only the tip of which projects from the 

 surface, but it has a long straight shaft almost as large as 

 that of the oar-shaped kind. The posterior margin of the 

 first and second lamellae are coarsely crenate, but that of 

 the third is smooth ; a ridge from each lamella passes 

 downward to the ventral bristles. 



The ventral bristles, as in the previous species, conform 

 to the type of the dorsal, being more slender forms with 

 oar-shaped tips. 



The posterior region of the body has about 34 bristled 

 segments, and tapers gently from the anterior to the posterior 

 end, but the latter is of considerable breadth and is gently 

 rounded to join the caudal tube. The dorsal surface is more 

 or less flattened aud marked by a rather broad median band 

 with transverse grooves, which are not opposite those between 

 the lateral lamellae — indeed, they alternate with these. The 

 ovoid anterior area is opposite the first, second, and part of the 

 third segments of the region, whilst posteriorly the median 

 band rises into an elevated rounded ridge, continuous with 

 the caudal tube. The branchiae form conspicuous dorsal 

 processes, the first seven or eight being noteworthy for their 

 great length. Their structure corresponds with that observed 



