164 Prof. M'Intosli's Notes from the 



h. Hetcrocirrus {Heterocirrus gravieri, sp. n.) dredged at 

 Station 29 oft" Cadiz^ to the west of the Straits of Gibraltar, 

 in 227 fatlioms, in the ' Porcuoitie ' Expedition of 1870, 

 appears to dift'er from any described. At this station, ac- 

 cording to Dr. Gwyn Jeffreys, there was an admixture of 

 northern and southern forms. The head is pointed in front 

 and constricted posteriorly, so that from the dorsum it is 

 almost cordate in outline. The mouth, as in allied forms, 

 opens a little behind the tip of the snout. The body is 

 about an inch in length, somewhat narrow and elongate, and 

 slightly flattened from above downward throughout, the tail 

 not being wider than the preceding region, and terminating 

 in a pointed extremity with the anus above it. The colour 

 in spirit is pale brown, darker at the tip of the tail. Ante- 

 riorly the dorsal bristles (PI. VI. tig. 3) are longer than in 

 allied forms with the exception of Chatozone, but they 

 become shorter posteriorly. A pair of tentacles occurs in 

 front and a pair of branchise on each side behind it. The 

 tentacle is darker, longer, and thicker than the others, 

 though apparently not differing in external structure. It 

 arises immediately behind the head and may be the homo- 

 logue of the grooved tentacle, e. g., of Dodecaceria ater. A 

 branchia springs just above it. 



The first foot has a distinct dorsal setigerous papilla and 

 a long tuft of simple tapering bristles which nearly equal 

 the diameter of the body. The ventral division has a similar 

 though shorter tuft. This arrangement continues for some 

 distance and then the characteristic hooks appear in the 

 ventral division. These (PI. V. fig. 3 a) are comparatively 

 long and slender, with a slight forward curve. The shaft 

 dilates a little from the base to the distal third, where a 

 slight backward curve and a diminution take place to the 

 neck. The tip has an enlargement beyond the neck, then 

 the posterior curve, in lateral view, forms a segment of a 

 large circle and again points forward at the hooked tip. 

 The anterior curve again is chiefly backward and then for- 

 ward at the terminal hook. The length of the distal region 

 in this hook is characteristic. A few bristles accompany 

 the ventral hooks to the posterior end. By-and-by between 

 the twentieth and thirtieth foot the hooks appear also in the 

 dorsal division, one or two of these organs accompanying 

 the bristles, which continue to the posterior end of the 

 annelid. 



This species inhabits a firm though thin calcareous tube 

 strengthened externally by grains of sand, foraminifera, and 

 fragments of shells. The interior of the tube is perfectly 



