BY WILLIAM A. HASWELL, M.A., B.SC. 275 



POLYDORA (LeUCODORE) POLYBRANCHIA. N. S. 



The head is of the same breadth behind as the segments 

 of the body. In front it becomes rather narrower, and ends 

 anteriorly in two low triangular lobes separated by a wide notch. 

 There are four veiy small rounded eyes. Running backwards 

 from the mouth is a narrow groove continued as far as the third 

 segment. The branchiae begin on the second segment of the body. 

 The large setfe on the fifth segment are ten in number and arranged 

 in two sets which differ from one another in shape and in direction. 

 The five which are directed towards the ventral aspect of the 

 animal end in a broad head having the form of an inverted cone 

 with an oblique base ; on the base of the cone are one or two small 

 conical elevations. The five which are directed more towards the 

 dorsal side are not so broad at the end and are gently curved in 

 the form of a hook with a blunt apex. The ordinary setae and 

 uncini are precisely similar to those of P. ciliata as figured by 

 Macintosh. The uncini or hooked setse begin on the seventh 

 segment ; there are from six to ten of them on each parapodium, 

 all with the apex directed outwards, except the most external, 

 which is very short, and has the apex directed inwards. Some of 

 the sette of the anterior parapodia are very long and filiform. 



The setaj are not unlike those figured by Eay Lankester (Ann. 

 Mag. Nat. Hist., (4th series) Vol. I., 1868) as those of P. calcarea, 

 and regarded by Macintosh (1) as belonging to a variety of 

 Polydora ciliata : but apart from the form of the boring setse, the 

 presence of branchiae on all the segments, together with the 

 absence of cephalic tentacles, seems to distinguish the present 

 species fi'om all hitherto described forms. Polydora cceca of 

 Oersted (2) resembles it in having " branchias in utroque corporis 

 parte," but has long prgestomial tentacles. 



The only sovtthern species of Polydora described is P. soctalis 

 of Schmarda (3) which has a pair of well-developed tentacles. 



(1) Ann. Mag. Nat. Hist., 1868. 



(2) " Zur Klassification der Anueliden." Vide Quatrefages, Hist. Nat. 

 Ann. II., p, 302. 



(3) Neue Wirbellose Thiere. I., ii., p. 64, pi. XXVII., fig 209. 



