36 Prof. M'IntosVs Notes from the 



by peristaltic contractions to the cardiac sac, whence it is 

 driven at intervals forward to the common branchial vessels 

 and by the separate trunks to the tips of the branchiae. It 

 returns by the same course and enters the lateral ventral 

 trunks, and passes to the ventral vessel, by which it is 

 distributed to the collar and the body generally " (Hasivell). 

 In Pomatocerus the abdominal region possesses the peri- 

 intestinal vessel and a minute ventral trunk. Anteriorly 

 the former splits into a large dorsal vessel or cardiac sac 

 and about 16 smaller vessels, which run on the wall of the 

 alimentary canal. Further forward the peri-intestinal vessels 

 join the dorsal trunk, thus making two main trunks, a large 

 dorsal and a small ventral. Then the dorsal bifurcates into 

 the two branchial, and so does the ventral, but Prof. Haswell 

 was uncertain whether the latter communicated with the 

 former as in Eupomatus. All the vessels possess a muscular 

 wall, and the blood in the majority is of a light green colour, 

 and contains certain clear oval bodies probably derived from 

 the epithelial lining of the A^essels. 



A pair of thoracic glands exist in this group as in the 

 Sabellidse. In Eupomatus and Serpula each has the form of 

 a brown body with its long axis directed longitudinally, the 

 posterior part with thinner clearer walls and an anterior 

 dark brown folded part. No opening into the ccelom was 

 made out by Prof. Haswell. In front the gland is continued 

 into the ciliated duct, which passes almost directly inward 

 to meet its fellow in the middle line, the common duct going 

 straight forward to open ventrally (dorsally) between the 

 bases of the branchiae. The gland is lined by large, granular, 

 nucleated cells, each furnished with a flagellum at its apex. 

 Haswell found the "true" segmental organs in all the 

 abdominal segments, viz., delicate pyriform sacs ciliated 

 internally, and opening externally on the sides of the seg- 

 ments by slit-like apertures having active cilia. No internal 

 aperture, could be made out. In Eupomatus each in the 

 female contained a group of ova at various stages up to the 

 fully developed egg. These segmental organs alternated 

 with the ovaries. In the males these sacs were always 

 empty. 



No feature is more distinctive of the Serpulids in contrast 

 with the Sabellids than the extreme transparency, thinness, 

 and minute serrations o the hooks. As a rule, they approach 

 in shape those of the Ampharetidae rather than those of the 

 Sabellidfe. The hard, smooth, calcareous nature of the tube 

 probably necessitates a special adaptation of a mobile torus 

 with flexible hooks, the fiee edge of which is beset with a 



