38 SCALIBKEGMA INFLATUM. 



preparations sometimes give a darker hue to the organs posteriorly. A careful descrip- 

 tion of these structures has been given, with figures, by Ashworth. 1 The cells are chiefly 

 occupied by bundles of fine rods, but a nucleus is also present. They open on the surface, 

 and are similar to the bacilliparus follicles of other annelids. 



The nephridia (Fig. 104) are in the form of slender tubes bent on themselves, with 

 small funnels. The funnels of the first three are situated on the anterior faces of the 

 second, third, and fourth diaphragms respectively. They extend throughout the body. 

 The nephridiopore of the first is just below and slightly anterior to the ventral division 

 of the fourth foot (Ashworth). 



Reproduction. — The gonads are very small and are described by Ashworth as present 

 on a thin sheet of tissue (probably representing a septum) between the nephrostome and 

 the body-wall. He could not distinguish the sex, however, until the cells had been shed 

 into the coelom and increased in size. 



Young examples appear sometimes to be devoid of gills (Ashworth's Irish example, 

 1909). 



This was one of the many additions to the Norwegian Fauna made by the acuteness 

 and patient industry of H. Kathke (1843), who gave an accurate description with excellent 

 figures of this interesting species. Amongst other points he compared the glandular 

 structures in the dorsal and ventral cirri to those on the dorsal edge of the foot in Nereis 

 Bumerilii. The coloration of his examples seems to have been less vivid than that of the 

 Hebridean forms, which were also larger. 



Kolliker in 1864 pointed out the identity of Scalibregma inflation, Rathke, and 

 Oligobranchus roseus, Sars. His specimens were yellowish, not reddish like those 

 found in the Outer Hebrides. 



Danielssen thought that this species was hermaphrodite, but as De St. Joseph 2 and 

 Ashworth observe this is a misapprehension. Danielssen noticed ova escape by a 

 rupture of the body-wall. Such an occurrence may be associated with the pelagic con- 

 dition assumed by the forms described by Ditlevsen. 



Wiren (1887) gives an account of the anatomy of this species along with other (4) 

 limivorous polychaats. His section of the body-wall is only diagrammatically outlined. 



An able account of the anatomy of this form, with excellent figures, is also given by 

 Ashworth. 3 He found Coccidian parasites imbedded in the cells of the loop of the 

 segmental organ. 



Ditlevsen 4 (1912) had an opportunity of examining recently between twenty and 

 thirty examples from the Danish expedition to Greenland, and they agreed with 

 Michaelsen's variety coreihrura, the bristles being extremely long, silky and soft. The 

 most interesting fact noted by this author is that these and many other examples were 

 found in September in a pelagic condition frozen in the ice at the surface (and dead), or 

 swimming in a hole with broken ice and water, and with their reproductive elements in 

 full perfection. The author is thus warranted in suggesting that IVlichael sen's variety 



1 ' Quart. Jouru. Micr. Sci./ vol. xlv, N.s., p. 248, pi. xiii, f. 8—11. 



2 'Ann. Sci. nat./ 8 e ser., xvii, p. 111. 



3 ' Quart. Journ. Micr. Sci./ vol. xlv, N.s., p. 237, pis. 13—15. 



* < Danmark Eksped. Gronl./ 1906-8, Bd. v, p. 423, pi. xxvii,figs.7, 8, 9; pi. xxx, fig. 21. 



