STYLARIOIDES PLUMOSA. 95 



The Stylarioides monilifera of Delle Chiaje 1 (1829) appears from its description to 

 be a closely allied form, but it is really a characteristically different species, for its long, 

 slender body is smoother to the naked eye, its surface-papillae being densely arranged and 

 minute, and its bristles and hooks likewise diverge. 



H. Rathke 2 (1842) gave a careful account of this species from spirit-preparations, 

 correcting 0. F. Muller's interpretation of the branchiae (Rathke's cirri) which he 

 described as ovaries. His figures of the external and internal structure are, on the whole, 

 accurate. 



Dr. Thos. Williams 3 (1852) in his Report considered that Trophonia was charac- 

 terised (in contrast with Lumbricas and Hirudo) by a great increase in the perivisceral 

 fluid, which performed the function of aeration. He did not interpret the greenish organs 

 as branchiae. 



Dr. Johnston (1865) drew the conclusion that, from the softness and flaccidity of its 

 body as well as from its structure, this form burrowed in the soil like Arenicola, yet most 

 of the examples procured at St. Andrews have been found between the layers of shale and 

 sandstone, but it delights in dark, odoriferous mud. 



The confusion in regard to this species is well illustrated by a reference to De 

 Quatrefages (1865), for it is described under three names with accompanying references. 

 He also mingled Brada and Siphono stoma with Pherusa and thus increased the complexity 

 of the subject. 



Verrill 4 (1873) describes a new species {Trophonia affinis) from Vineyard Sound, 

 U.S.A., which seems to approach the British form very closely. 



Levinsen (1883) regarded the Trophonia jiahellata of Tauber as a young example of 

 Stylarioides plumosa., and he ranged the T. arctica, T. borealis, and T. rugosa of Hansen 

 under the latter species. 



In 1887 Wiren gave an account of the structure of this species as one of his limi- 

 vorous polychaetes. Excellent figures of the general anatomy accompanied the description. 



Cunningham and Ramage (1888) describe the circulatory system and the heart-body 

 in this species, as well as the structure of the single pair of nephridia in front. They 

 could not find a nephrostome. They also mention the male and female gonads which 

 occur in the seventh and eighth segments. The ovaries are green and the testes pale 

 yellow. Cunningham 5 further describes a thin vessel (his homologue of the dorsal) 

 running on the inner surface of the body-wall, receiving transverse vessels from the 

 intestine, and opening into the dorsal side of the heart. The cardiac body he found to be 

 composed of cylindrical cellular cords resembling nephridia. The blood contains small 

 oval nucleated corpuscles. 



The Stylarioides hirsutus, of Lo Bianco 6 (1893), would seem to approach this species. 

 It is difficult to say what his Brada parthenopeia may be. 



1 f Memorie/ vol. iv, p. 178, Tav. liii, fig. 5. 



2 ' Neuste Sclirif. Naturforsch. (resell, in Danzig/ Bd. in, p. 86, Taf. iv, figs. 2 and 5. 



3 ' Kep. British Association' for 1851, pt. 1, p. 202. 



4 ( Rep. Fish. Comm. U.S.A./ p. 605, pi. xiv, fig. 75. 



5 ' Quart. Jonrn. Micr. Sci./ vol. xxviii, n.s., p. 260. 



6 < Atti R. Accad. Sc. Nap./ 2 ser., vol. v, JSTo. 11, p. 42, Tav. h, fig. 5, and Tav. hi, fig. 11. 



