94: F. W. GAMBLE, M.SGL, AND J. H. ASHW0RTH, B.SC. 



appears to correspond, in position, to the characteristic tufts of hairs on 

 the ventral setae of the Maldanidse. 



According to the age of the specimen the ventral setse differ in shape, 

 and in the development of the toothed ridge. In setse from a small 

 specimen (17 mm. long) the apex was bent more sharply on the shaft 

 than in old examples, and the teeth were very prominent (PL VIII, Fig. 

 9). Apparently the production of fresh ventral setse goes on slowly 

 throughout-, life, and the form which they assume before being cast oiit 

 of the body, varies at different ages Their size of course varies 

 with the age of the worm to which they belong (see PL VIII.), but in a 

 worm of average size their length is about '5 to - 8 mm. 



3. General Anatomy of the Internal Organs (PL VII.). 



In opening the body-cavity by a dorsal incision, the middle part of 

 the alimentary canal is usually forced out through the cut by the 

 pressure of the somewhat viscous coelomic fluid. Normally this portion 

 of the canal, being longer than the section of the coelom in which it 

 lies, is swung to and fro by the movements of the body. This freedom 

 of motion is ensured by the absence of mesenteries, by the absence of 

 any vessels running from the body-wall into the dorsal vessel, and by 

 the length and flexibility of the branchial and nephridial vessels, which 

 are the only connection between the stomach and the body-wall. 



The coelom is exceedingly spacious, and continuous from one end of 

 the body to the other. In front it is divided transversely by the 

 origins of the buccal retractors (B. Sh.), which form a sheath round 

 the proboscis, and by three septa or diaphragms (Pis. VI \. and VIII. , 

 Figs. 5 and 6). The first of these septa (Bphm.) is placed obliquely, 

 arising below behind the level of the first neuropodium, and being 

 inserted dorsally in front of the first notopodial sacs. The result of 

 this arrangement is that between the first and second diaphragms two 

 pairs of setal sacs occur, caused by the forward shifting of the upper 

 edge of the first diaphragm (Fig. 5). The second and third are inserted 

 both above and below, opposite the second groove behind the second 

 and third chsetigerous annuli. Between the first and second diaphragms, 

 dorsal and ventral mesenteries occur, supporting the corresponding 

 vessels ; and it will be noticed that the dorsal mesentery ends in front, 

 exactly where the first diaphragm would be inserted if it corresponded 

 with the other two. The third diaphragm is perforated by the funnels 



