228 MAGELONA PAPILLICORNIS. 



Besides the two conspicuous tufts of long, provisional bristles in front, there are four 

 considerable tufts of transparent bristles in the middle of the body. The terminal 

 region is simply rounded and pigmented, and a band or a touch of pigment at each side 

 indicates the other segments. 



Dr. Fritz Muller, 1 in 1858, in his observations on the annelids from the Island of 

 St. Catherine, off the coast of Brazil, briefly mentions this remarkable form. The type 

 was next referred to by Dr. Edouard Claparede 2 in his account of a larval form which he 

 found at St. Vaast-la-Hougue, on the west coast of France. The same singular species, 

 however, as that indicated by the first-mentioned author was originally discriminated by 

 the late Dr. George Johnston, 8 of Berwick, from preparations forwarded by the dis- 

 tinguished botanist, Dr. Greville, but as his description was not published until 1865, long 

 after his death, the name (Msea mirabilis) which he gave lapses. 



Young stages of this form were described by W. Fewkes 4 (1866) as larval forms of 

 Prionospio, but, as Griard 5 has shown, they are referable to this species. 



Lo Bianco's figure (1893) 6 of the anterior region presents an injured abnormally 

 contracted snout, and the structure of the tentacles is indistinct. 



Between May and October various stages of the larval and post-larval Magelona are 

 procured in the tow-nets in St. Andrews Bay, and two of these are described and figured 

 elsewhere. 7 



Mesnil (1896) considers that Magelona has two important characters of the Spionidse, 

 viz. those of its tentacles and its winged hooks. Its aberrant characters are : — 



(1) The form of its prostomium; (2) the presence of two vessels in its tentacles, and 

 the absence of a ciliated line along these organs ; (3) the division of the body into two 

 distinct regions. The other aberrant character is the absence of branchiae. It 

 approaches Spiophanes by the long and fine lamellse of the feet. He thinks it interesting 

 in regard to the evolution of the Chastopteridas, especially in connection with the 

 distinct regions of the body, but this is doubtful. The feet in the ninth setigerous 

 segment resemble those of the second, and the form of the feet of the eighth is inter- 

 mediate between that of the seventh and the ninth. A survey of the structure of the 

 Chastopterids, however, shows that there is no continuity of the families. 



Mesnil is of opinion that the embryology of Magelona confirms the Spionid relation- 

 ships. He can verify the exactitude of the figures of Claparede, Fewkes, and Mcintosh. 

 In the larva the prostomium is short, and bears four eyes. The winged hooks are 

 found in a larva of thirty segments. In the tenth one winged hook occurred ventrally, 

 and in the fourteenth two dorsally. Claparede again found six eminences at the anus 

 indicating six cirri. The larva differs from that of other Spionids in the great develop - 



1 ' Arch. f. Naturges./ 1858, p. 211. 



2 'Beobacht. Anat./ etc., 1863. 



3 ' Cat. Worms Brit. Mus./ p. 278. 



4 'Annals Lyceum Nat. Hist. New York/ vol. viii, p. 320, pi. vii, fig. 19. 



5 'Bull. sc. Fr. et Belg./ t. xvii, p. 98, and ( (Euvres Div./ p. 192. 



6 ( Atti R. Accad. Sc, Nap./ ser. 2, vol. v, Tav. iii, fig. 2. 



7 ' Quart. Journ. Micr. Sci./ vol. xxxvi, N.S., p. 68, pi. viii, figs. 1 — 3. 



