THE ANATOMY OF SCALIBREGMA INFLATUM. 247 



are divided from each other only by shallow grooves, para- 

 podia have not yet been formed (fig. 6) . Just in front of these 

 there are a few segments (about four) in which the parapodia 

 have only been recently formed, and in these the dorsal cirri 

 are considerably larger than the ventral ones, — in fact, the 

 latter have not yet appeared in some segments which possess 

 dorsal cirri of moderate size. The dorsal cirri are thus 

 formed before the ventral ones. The notopodium and a few 

 of its setfB are formed before the neuropodium appears. 



The cirri are sensory structures, and from their earliest 

 appearance are supplied with stout branches from the lateral 

 nerves given off in each segment from the ventral nerve-cord 

 (PI. 14, fig. 16). 



On each cirrus, a little behind its tip^ there is a distinct 

 darker area, which is somewhat oval, reniform, or pyriform 

 in shape (fig. 8). In most specimens this area is very 

 obvious, on account of its brown or black colour, but in some 

 its colour is much lighter. This is not a structure separate 

 from and standing out from the cirrus, as the description by 

 Rathke (pp. 185, 186) would lead one to believe. The 

 darker appearance of this portion of the cirrus is due to the 

 presence within it of a collection of special gland-cells, the 

 dark-coloured glandular mass being visible through the semi- 

 transparent walls of the ciri-us. Rathke examined and 

 reported on these dark masses in considerable detail, and 

 rightly inferred that they are similar in structure to the 

 black or brown spots on the notopodia of Nereis dumerilii, 

 which he had described on a previous page as glandular 

 (Hautdriisen). Sars does not mention them, but Danielssen 

 (p. 75) re-examined them, aud came to the conclusion that 

 they are testes, as they are composed of a lai-ge number of 

 somewhat coiled tubes, filled with minute elongate bodies, 

 which he took to be " /.oosperms." Rathke's interpretation 

 is the correct one ; these dark bodies are parapodial glands, 

 the secretion of the cells of which is in the form of minute 

 slender rods (see p. 248). Mcintosh (1885, p. 360) remarks 

 that these curved bodies in the parapodia of Scalibregma 



VOL. 45, PART 2. NKW SKKIES. S 



