REPORT ON THE MYZOSTOMIDA. 9 



69. Myzostoma cirripedium, Graff. 



Myzostamacirripedium, Graflf, Trans. Linn. Soc. Lond. (Zool.), ser. 2, vol. L pp. 444-445, fig. 19, 



1885. 



This species, found on Metacrinus roUmdus, P. H. C, is closely allied to Myzostoma 

 wyville-ihomsoni (No. 30), but differs from all forms hitherto described in the possession 

 of parapodial cirri. 



70. Myzostoma giganteum, Nansen. 



Myzostoma giganieum, Nansen, Bidrag til Myzostomernes Anatomi og Histologi, Bergen, 1885. 

 Very like Myzostoma gigas (No. 11), found on Antedon prolixa, Sladen.^ 



71. Myzostoma graffi., Nansen. 



Myzostoma graffi, Nansen, Op. eif. 



Resembling Myzostoma marginatum (No. 15), found on Antedon prolixa, Sladen. 



72. Myzostoma nanseni, n. sp. (PL II. figs. 2, 3). 



This beautiful Myzostoma, which I have named in honour of JVIr. Fridtjof Nansen, 

 has a close resemblance to the Myzostoma folium described in the Report. The single 

 specimen before me measures 8 mm. in length, and in its uncontracted state must have been 

 about 3 mm. in breadth, so that it is not so elongated as Myzostoma folium. It differs 

 from the latter, further, at first sight, in the absence of a distinctly defined marginal 

 zone. The body disc, which is about 1 mm. in thickness, seems to thin off imperceptibly 

 into the finely notched margin. The marginal notches are besides more individualised 

 and pointed, not blunt as in the species above referred to. A flat longitudinal groove 

 marks the middle line of the ventral surface, while the median dorsal line projects 

 conspicuously only in the region of the very strongly developed pharynx (p/i). 



The parapodial insertions are marked on the back by five pairs of lateral elevations. 

 The colour is a uniform dirty brown with a slight reddish tinge. 



The mouth is situated not far from the anterior end, but the cloacal papilla (cZ) lies 

 at the commencement of the last quarter of the body. The parapodia (p) are very strong, 

 and disposed at equal intervals in two longitudinal rows between the mouth and cloacal 

 papilla. The round suckers (s) are very slightly developed, and hardly recognisable 

 with a lens. 



Found lying loose in spirit with a black Actinometra (n. sp.) and several other 

 Comatulse from Moluccas (K. zool. Genootschap, Amsterdam). 



1 This species was referred to by Nansen as the Antedon celtica of Marenzeller and of Sladen ; but Dr. P. H. 

 Carpenter, who has received specimens of it from Nansen, identifies it with Antedon prolixa, Sladen, 



(zool. chall. EXP. — PAET LXI.— 1887.) Ppp 2 



