GATTYAXA CIRROSA. 289 



seen along the mid-dorsal line even when no distinct band is present anteriorly and 

 posteriorly. 



Feet. — The tentacular cirri agree with the median tentacle. The basal region has the 

 usual small tuft of serrated bristles (corresponding to the dorsal) with a spine. They 

 are somewhat short and rather stout bristles, with rows of short spikes towards the tip. 



In the second foot the dorsal bristles are shorter and more roughly spinous than in 

 the typical foot. The latter is probably partly due to their shortness and greater curvature. 

 On the other hand, the ventral bristles have much more elongated tapering tips than in 

 the typical foot. The ventral cirrus has a few short clavate papillae throughout the whole 

 series. 



The third foot presents a considerable change in the dorsal bristles, which now show 

 the strong series with curved, serrated tips next the body, and the slender series with 

 tapering tips adjoining the ventral division. The dorsal cirrus is somewhat shorter and 

 thicker than in the fully developed foot. Both shafts and tips of the ventral bristles are 

 still much more slender than in the average foot. 



In the fourth foot a near approach to the condition in the typical foot occurs, 

 though both dorsal and ventral bristles are more slender. 



In the typical foot the dorsal division is bluntly rounded and turned upwards (Plate 

 XLII, fig. 27), the spine, which is sheathed in skin, passing out as a slender process 

 towards the inferior edge of the bristles. The dorsal bristles are rather slender 

 (Plate XXXVII, fig. 18), have a long tapering tip, with rows of spines, the extremity 

 being hair-like. The ventral division, on the other hand, has a somewhat triangular edge, 

 the spine, which is sheathed at the base, and forms an independent process posteriorly, 

 passing outward at the apex of the triangle. The ventral bristles show tips increasing 

 in length from below upward, the superior bristles (Plate XXXVII, fig. 16) having 

 more delicate tapering tips and more numerous rows of spines, while the tips are slightly 

 hooked, the intermediate series (Plate XXXVII, iig. 17) often having a slight enlargement 

 below the hooked tip. In large examples from deep water beyond St. Andrews Bay the 

 smooth tips of the ventral bristles are somewhat shorter and broader. In contrasting 

 these with the bristles of Arctic examples, the tips (that is, the region beyond the spines) 

 of the latter are longer, and the bristles, both dorsal and ventral, are in some cases rather 

 stouter. In the Arctic forms also the cilia on the cirri are somewhat longer. 



In the posterior feet the tips of the ventral bristles again become elongated and the 

 shafts more slender. In the last foot, indeed, the tips are so attenuate that, leaving the 

 shafts out of sight, the curve of this region is almost the only distinction by which they 

 can be recognised. The ventral cirri also are more elongate. 



A curious ochreous appearance occurs in certain forms from Godhaven, Greenland, 

 in which the tips of the dorsal bristles are covered with a minutely granular reddish- 

 brown deposit, probably derived from their surroundings. The same structure coats the 

 cilia of the cirri and scales. 



The figure of the foot in Malmgren's paper does not show the upper spine, and in 

 the ventral division the conical process for this structure is absent. 



Parasites. — Loxosoma is not uncommon on the bristles and feet of the Arctic forms 

 and those from the Gulf of St. Lawrence. 



