Gotlx) Marine Lahoratory^ St. Andrews. 169 



body is rounded dorsally, slightly flattened ventrally, and 

 the latter surface has a median groove. Both dorsal and 

 ventral bristles (PI. VII. fig. 8) are throughout capillary, and 

 little difference exists between the most anterior and those 

 at the tip of the tail. This, therefore, belongs to the 

 first series of De St. Joseph, viz., those with capillary bristles 

 throughout. 



Chaetozone setosa, var. canadensis. Stations 32-34 — 1873. 



In this form, which has a general resemblance to C. setosa, 

 though the body is more flattened posteriorly, the anterior 

 bristles diiferfrom those of C. setosa, for example at the tenth 

 foot in having a distinct curve at the end of the shaft, and 

 the long tip widens into a flat blade (PI. YII. fig. 9), which 

 theu tapers to a fine tip; the whole, however, is considerably 

 shorter than in the typical C. setosa. The general arrange- 

 ment of the posterior hooks resembles that of C. setosa, 

 though the crotchets (PI. VII. fig. 9 a) are considerably 

 larger and similarly alternate with a long capillary bristle 

 (PL VII. fig. 9^). It would be diflScult to draw a specific 

 distinction, however, from mere size. 



Chatozone whiteavesi. 



Dredged in the Gulf of St. Lawrence, Canada, by 

 Dr. Whiteaves at Station A. 6 in 1872. 



This species has much of the appearance anteriorly of 

 Clicetozone setosa, tbe snout being acutely pointed, and the 

 tentacles and branchiae being similar. The body is rounded 

 dorsally in front, then is somewhat flattened, and again is 

 rounded toward the tail, which is only a little tapered, and 

 has a terminal anus with two small rounded papillae ventrally. 

 The ventral surface of the body is marked by a median 

 groove from end to end, whilst the sides are flanked by tufts 

 of long capillary bristles from the front to the middle of 

 the body, and by shorter capillary bristles from the middle 

 to the tip of the tail. This arrangement at once differentiates 

 the species from C setosa and allied forms, for their crotchets 

 are conspicuous posteriorly. The gut shows through the 

 integumentary lajers in the region behind the middle — 

 especially dorsally — the colour being dull pink. 



The bristles throughout are capillary, the dorsal in front 

 (PI. VII. fig. ]0) being considerably longer than the ventral 

 and stronger than those in the succeeding region. Both 

 dorsal and ventral tufts are shorter in the middle of the 

 body, and the disproportion between dorsal and ventral is 

 less marked, whilst posteriorly they are almost equal. 



