Dr. Johnston on British Nereides, 147 



distinct, rounded and entire in front, with four eyes placed in a 

 square, the anterior pair more widely set than the posterior : 

 antenncE three, elongate, filiform, clothed with minute cilia, un- 

 jointed : proboscis apparently without teeth or other armature : 

 segments numerous, narrow, incised at their junctions ; the post- 

 occipital with a pair of tentacular cirri on each side, one-half the 

 length of the antennse ; the cirrus of the following segment elon- 

 gate, antenniform : feet uniramous, short, entire, armed with a 

 single fascicle of retractile simple unjointed bristles ; the superior 

 cirrus longer than the breadth of the segments, obscurely marked 

 with a few transverse lines or wrinkles, but not in any degree 

 moniliform ; the inferior cirrus small, and not projecting much 

 beyond the foot : tail tapered, tipped with a pair of styles. 



This little worm always kept its antennae twisted up in a spiral 

 manner, so that it was not easy to get a distinct view of their 

 number and location : they differ remarkably from those of the 

 preceding species in their greater development ; and it was easy to 

 see, with a magnifier of no high powers, that they were clothed 

 throughout with fine cilia. 



Plate IX, fig. 3. Syllis prolifera of the natural size. Fig. 4. The same 

 magnified ; 4 h, the head and anterior segments ; 4 *, the middle segments ; 

 4 t, the posterior extremity and styles. 



Glycera, Savigny. 



Char. Body lumbriciform, attenuated at both ends, the rings 

 numerous, narrow : head conical, bulged at the base, prolonged 

 into a sort of annulated horn with four minute equal antenna on 

 the apex: tentacular cirri none: mouth inferior; the proboscis 

 very large, clavate, two-jointed ; the terminal joint smooth, the 

 basal joint elongate, villose with minute papillse : feet uniform, 

 obsoletely biramous, setigerous, with a short superior and infe- 

 rior cirrusy and sometimes branchial papillary processes : tail with 

 a pair of short styles. 



In all the Nereides which we have hitherto described, the head 

 is to be readily distinguished by its enlarged form and its dissi- 

 milarity from the first segment ; but in the Glycera there is no 

 marked line of separation between these parts. The head has the 

 appearance of a small pointed horn, and is indeed so like the an- 

 terior end of the earth-worm, that we cannot but perceive, in this 

 sameness of character, a certain approximation to a junction be- 

 tween the families to which the Glycera and earth-worm respec- 

 tively belong. Yet though this is unquestionable, still the Gly- 

 cera is not the nearest connecting link, for there are other Anne- 

 tides errantes which partake more of the habits and character of 

 the TerricolcB. 



1. G. alba ; body most attenuated anteriorly ; jaws four ; supe- 



M2 



