i. Euphrosyne pilosa Horst. PI. I, figs. i — 6; PI. VI, fig. i. 



HORST, Notes from the Leyden Museum, vol. XXIII, p. 220. 



Stat. 40. Paternoster-islands. 3 specimens. 



A slender, pelagic worm, measuring at the most S 1 ^ mm. in length and 2 l /„ mm. in breadth 

 (without bristles), with six cylindrical, undivided branchiae on each side. The dorsal cirri situated 

 in front of the branchiae, longer than these; the lateral one corresponding to the interval 

 between the third and fourth branchiae. The dorsal fascicle contains ringent bristles of the type 

 of E. foliosa and forked ones, with small spines on their shaft. Some of the ventral bristles 

 slender and elongated, as long as two thirds of the breadth of the body. The caruncle three- 

 lobed, extending till segment IV. 



Among the numerous specimens of E. sibogae (see afterwards), collected with the townet 

 near the Paternoster-islands, I found three individuals of an other species, immediately recognizable 

 by the strong development of its bristles. The largest specimen measures 8 1 /» mm. in length 

 and 2 1 /., mm. in breadth (the bristles not included); the diameter of its bare medio-dorsal field 

 is about one third of the total breadth. The number of its segments amounts to 22. The 

 caruncle (PI. I, fig. 1) terminates in three cylindrical lobes, the middle one of which extends to 

 segment IV, the lateral ones reaching only the third one. The unpaired tentacle, arising in 

 front of the large dorsal orange-coloured eyes, is very long; with its slender terminal joint it 

 stretches till the posterior end of the median caruncle-lobe. The ventral eyes are remoted from 

 the front by an interval, which is about a third of the space between the frontal end and the 

 mouth; the palp-plates are oblong, pyriform. 



The dorsal region of each segment carries on both sides six cylindrical, undivided 

 branchiae, the outermost of which is the shortest, about half as long as the other ones 

 (PI. I, fig. 2, 6). In each branchia two large blood-vessels are visible, connected by a number 

 of transverse branches and upward passing the one into the other at a rather great distance 

 from the tip. The dorsal cirri (PI. I, fig. 2, d. c) are long and slender, projecting beyond the 

 branchiae; they stand in front of them, the lateral one corresponding to the interval between 

 the third and fourth gill. There is a doublé row of forked bristles, provided with small spines 

 on their shaft; they all are not of the same length and in the largest of them (PI. I, fig. 3) 

 the longest limb has a somewhat greater length in proportion to the shorter one than is 

 the case in the smaller bristles. Moreover the dorsal series contains some ringent bristles 

 (PI. VI, fig. 1), with a very slender stalk, of the type of E. foliosa 1 ); however the shortest 

 limb in E. pilosa is more blunt, almost semilunar, and the longest limb with its inferior grooved 



1) I think we can recognize two kinds of the remarkable serrated bristles, that characterize the genus Euphrosyne and that 

 probably are different in each of its species (see PI. VI) ; some of them (as in E. borcalis) not much deviate from the common bind bristle, 

 by having both Jimbs of the fork only slightly bent and thickened, while in others (as in E. foliosa) the shortest limb of the fork is 

 more or less club-shaped and the largest one strongly curved and enlarged. Johnson, in his "Pacific Coast Annelids", calls these bristles 

 "ringent", what I think to be a very expressive name; they had already been compared by Haswell (1879) with a bird's head. His 

 statement, that in E. mastersü these ringent bristles should also be present in the ventral fascicle is probably a mistake, for it should 

 be the first example, as far I am aware of. 



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