GLYCERINE. 471 



setigerous region with two fan-like groups of compound bristles, which are arranged in 

 three divisions, an upper series of five or six with comparatively short tips, a second and 

 larger series with longer, finely tapered tips, and a ventral series with long tips dor sally, 

 shorter ventrally. 



A great increase in the lamella at the inferior setigerous lobe occurs at the seventieth 

 foot, so that in outline the parts are broadly lanceolate. The bristles are longer, more 

 slender, and the terminal pieces finely tapered. The lobe also extends much further 

 beyond the ventral lobe than in the fiftieth foot. The characteristic bristles (Plate 

 LXXXV, figs. 2 and 2 a) now project from the lower superior lobe, it and the upper 

 having a broadly conical outline. 



A considerable change occurs at the one hundredth foot, for the lower lobe now far 

 exceeds the superior in bulk, the broadly lanceolate outline being due to the approxima- 

 tion of the two flaps. The upper and lower bristles have shorter tips, the intermediate 

 have very attenuate tips. The ventral cirrus is proportionally smaller. In the superior 

 division, again, the setigerous lobe has assumed the form of a short and broad cone (Plate 

 LXXV, fig. 13 c), with the bristles projecting freely. The dorsal lobe is small. The 

 great length and slenderness of the tips of the ventral bristles posteriorly is a feature of 

 note (Plate LXXXV, fig. 2 c). 



The foot retains, with modifications, the structure just mentioned to the posterior 

 end, the characteristic dorsal bristles projecting still more prominently, and with a 

 distinct curve below the hook at the tip, which has a delicate process (Plate LXXXV, 

 fig. 2 b). 



A change in the length of the foot occurs about the sixty-fifth segment, for there- 

 after it becomes considerably longer, and remains so proportionally to the posterior end. 



Reproduction. — In an example dredged in Bressay Sound in July, the body was filled 

 with advanced ova. In the same month another of small size (l\ in.) dredged in 110 

 fathoms off the Blasquet, S.W. Ireland, had well-developed ova. Large ova also were 

 present at the beginning of the same month in an example of average size from Balta 

 (fifty fathoms). Another at St. Andrews on 16th June had numerous large ova in the 

 coelomic space. 



It is remarkable to find such slight differences between the Gli/cinde trifida of the 

 c Challenger ' l from Queen Charlotte Sound, near Long Island, New Zealand, and the 

 British form. 



Verrill's Eone gracilis from Vinyard Sound 2 does not seem, so far as the description 

 goes, to differ materially from the foregoing. 



Family XIII. — Glyceric. 



Head long, in the form of a pointed ringed cone, with four small tentacles at the 

 tip, and having a central space communicating with the body-cavity. Several authors 

 state that " at the base of the snout are a pair of palps," and Ehlers observes that they 

 are retractile. Body elongated, rounded, slightly tapered towards the head, and more 



1 Op. cit., p. 341. 



3 ( U. S. Comm. F. and F./ 1873, p. 596, 1873. 



