102 Prof. M^Intosli's Nolesfrom the 



firm, rouiulecl, and glandular^ the ventra) streak forming a 

 rid^e rather than a groove. Each has a sliort row of houks 

 and a tuft of rather long bristles. The bristles are in two 

 groups — a stronger golden seiies, with nearly cylindrical 

 shafts, except the somewhat narrowed region at the base, 

 tapering and slightly curved tips, with narrow wings; and a 

 more delicate series, having slender tips witli a trace of 

 wings. The hooks of these three segments differ from tl»e 

 succeeding hooks in the absence of the gular bristles, in the 

 great size of the main fang, and in the rudimentary con- 

 dition of the spikes on the crown, all these features, with 

 the comparatively narrow distal region, being conspicuous in 

 those of the first bristled segment. The main fang leaves 

 the neck at more than a right angle and its distal outline is 

 sinuous so as to resemble a foot. A slight swelling occurs 

 on the throat at its base. In these segments (three 

 anterior) the bristles and hooks are in front of the boundary 

 of the anterior third and lateral in position. 



The fourth segment is equally glandular, though short, 



and its row of houks is longer. The shafts of tiie hooks 



still retain their great length and curvature, increasing in 



size from the somewhat slender basal region to the broad 



shoulder, then contracting at the neck, which slighth widens 



in its passage forward to the crown. The great fang comes 



off more nearly at a right angle than in the anterior leet, is 



proportionally less, is evenly curved on its distal margin, and 



has four teeth on the crown above it. JNloieover, tlie gular 



bristles spring from the throat immediately beneath the great 



fang, curve forw ard to its tip, and bend upward above it. 



The distal region has straight striae superficially at the end, 



oblique stiife in the deeper part of the neck, and the shaft is 



longitudinally striated. The hooks renu^in for the most part 



similar in the fifth, sixth, and seventh, except that in some a 



tendency to differentiation of the crown «ith its four smaller 



teeth and a differentiation in the trend of the posterior outline 



are observed. The typical hook shows a narrower neck above 



the prominent shoulder, a shorter distal region or neck, which 



is broad at the crown and has at least five (six, Aricidsson) 



teeth behind the great fang, but the gular bristles retain 



their position close to the base of the great fang and without 



diflerentiation of the outline at their base. The hooks of the 



small form from St. Magnus Bay have a higher crown than 



those from Canada, thus resembling those from the posterior 



region of large examples. 



The posterior hooks, for instance those of the last row, 

 differ chiefly in their smaller size, the shafts being shorter, 



