Dr. Johnston on British Nereides. 1 17 



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

 square, the anterior pair more widely set than the |)o.sterior : 

 anteniue three, elongate, Hliforni, clothed with minute cilia, un- 

 jointcd : proboscis ap|)arcntly without teeth or other armatiue : 

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

 occipital with a i)air of tentacular cirri on each side, one-half the 

 length of the anteinia^; the cirrus of the following segment elon- 

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

 single fascicle of retractile simple unj(nnted hristles ; the superior 

 cirrus longer than the hreadth of the segments, obscurely marked 

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

 moniliform ; the infei-ior cirrus small, and not projecting much 

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



This little worm always ke])t its antennre twisted uj) in a spiral 

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

 number and location : they differ remai'kably from those of the 

 preceding species in their greater develoj)ment ; and it w as easy to 

 see, with a magnifier of no high })owers, that they were clothed 

 throughout with fine cilia. 



Plate IX, fig. .3. SijUis proUferu of the natural size. Fig. t. Tlie same 

 magnified ; \ h, the head and anterior segments ; 4 s, the middle segments ; 

 4 ty the posterior extremity and styles. 



Glycera, Savigny. 



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

 numerous, nan-ow : head conical, bulged at the base, prolonged 

 into a sort of annulated horn w ith foiu- 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 papilke : feet uniform, 

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

 rior cirrus, 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 Hne 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- 

 lides errantes which partake more of the habits and character of 

 the Terricola. 



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



M2 



