Gatty Marine Laboratory, St. Andrews. 37 



eusheaths the base of the branchiae. At the dorsal fissure 

 the thickeued edges, after the collar ceases, are carried 

 downward, and end in a point above the inflection of the 

 firm rim to which the branchiae are attached, and which 

 has the outline of a horse^s hooF, tlie rounded ventral arch 

 forming the front and the indented dorsal region the frog. 

 After the brancliise are shed, a small papilla is usually found 

 in the mid-dorsal, and a larger in the mid-ventral line of 

 the thickened inner rim. The mouth lies above the ventral 

 papilla. 



The body of this form is generally more rounded than 

 in the Sabellids proper, reaches the length of 5-6 inches, 

 and has the thickness of a strong goose-quill. The 

 segments are from fifty to ninety. The outline is 

 somewhat spindle-shaped, for, though the cephalic lobe 

 is truncate, the body tapers to it, as well as more distinctly 

 toward the tail, at the point of which is the anus, which 

 in the younger examples sometimes shows two papillae — a 

 smaller dorsal and a more prominent ventral papilla. The 

 deep dorsal fissure is continued to the second segment, 

 where it is dilated, and from this the mid-dorsal groove 

 passes backward to the anterior border of the eigiith seg- 

 ment, where it inclines to the right, cutting off in its course 

 ventralward a narrow portion of the ninth segment, and, 

 reaching the mid-ventral liue in this segment, thereafter 

 proceeding to the tip of the tail, the last part of its course 

 being generally more deeply grooved in the preparations. 

 The body of the fresh specimen is pale pinkish, and in the 

 newly-preserved form is of a pale skin-colour. 



The branchiae vary from twelve to thirty-six on each side, 

 and are connected together almost to the tip by a membrane, 

 the dorsal fissure, however, causing a gap in the funnel. In 

 preserved examples the filaments are often slightly spiral 

 and the tips are incurved. The filament is stiffened by a 

 chordoid camerated axis as in Subella, but it is not less in 

 diameter. The tip of each process is characteristically 

 formed with a broad wing at the base and tapering to a fine 

 tip. A slender axis, apparently from the chordoid skeleton, 

 passes along the centre of the bare flattened tip almost to 

 its extremity. The pinnae are long, even to the base of the 

 flattened terminal process, and have a central (chordoid) 

 axis, the tip being smoothly rounded or occasionally slightly 

 enlarged. The pinnae at the bases of the filaments (that is, 

 near the mouth) are elongated, the last one or two being so 

 long as to resemble tentacles. When a suitable example is 

 observed the slender tentacles arise at each side of the mouth. 



