POLYCH^TA SEDENTARIA OF THE FIRTH OF FORTH. 677 



and numerous, form a kind of palisade round the head region, which is com- 

 pletely retractile. In the rest of the somites the dorsal fascicle contains only 

 4 or 5 bristles, which terminate in slender points : a number of the epidermic 

 projecting cells, of a special form, surround the dorsal bristles, climbing up them, 

 as Claparede says, like a climbing plant up a tree, and terminating at the 

 same level as the bristles. 



Flabelligera affinis, Sars. 



Flabelligera affinis, Sars, 1829, Bidrag til Soedyrenes Naturalh., i. p. 31 ; 



Beskriv. og. Jakt, p. 47. 

 Siphonostomum vaginiferum, R. Leuckart, Arch. Naturg., xv. 1, p. 164. 

 Siphonostoma uncinala, Johnston, Cat. Brit. Mus., p. 223. 

 Flabelligera affinis, Malmgren, Annulata Polychseta, p. 193 ; M'Intosh, 



Fauna of St Andrews. 



Dredged on Middle Bank in August 1886. Also found occasionally at 

 Granton in the Laminarian zone under stones, at low water, spring tides. 



It seems in the highest degree probable that the S. diplochaites described 

 by Clarapede (diet, de Naples, p. 369) is the same species as the present 

 one; that the Mediterranean and northern forms are all of one species. That 

 this is so is shown by comparing the synonymy given by Malmgren (Ann. 

 Polyc.) and Claparede : both give Cldorcema Edwardsi, Dujardin, as synonyms. 

 Malmgren gives Siphonostoma uncinata, Johnston, as a synonym : Johnston 

 and Claparede both give S. Edwardsi, Grube (Fam. Annel), as a synonym. 



In Siphonostomum the arrangement of the pseudhsemal system is closely 

 similar to that described in Trophonia, but there are some slight differences. 

 The dorsal vessel is not so large, and is confined to the anterior part of the 

 body. At the extreme posterior part of the body no distinct dorsal vessel is 

 present ; the transverse lateral vessels of the integument form a network. But 

 the anterior part of the vessel, as in Trophonia, receives the lateral vessels of the 

 integument, and the vessel joins the heart a short distance in front of its 

 posterior end. Into this vessel, near its junction with the heart, open several 

 median vessels, bringing blood from the lateral vessels of the integument in 

 front of the junction. 



In Flabelligera affinis there are 6 pairs of gonads, instead of 2 as in 

 Trophonia. They have the same relations as in the latter genus ; each is 

 supplied by a central vessel from the ventral longitudinal trunk, and the longer 

 posterior gonads are bound up together with the loop of the intestine into a 

 cylindrical mass, by means of a thin confining membrane. As in Trophonia, 

 the ovaries are green, the testes white. 



The same bending of the intestine occurs as in Trophonia ; the blood in the 



