POLYCH^TA. — BENHAM. 177 



II. — Description of the Genera and Species. 



Family HESIONID^. 



Genus Hesione, Savigny. 



Hesione splendida, Savigny. 



Hesione splendida, Savigny, System, des Annelides, 1820, 

 p. 40, pi. iii., fig. 3. 



Hesione ceylonica, Grube, Proc. Zool. Soc, 1874, p. 327. 



Hesione pacifica, M'Intosh, Chall. Rep., Zool., xii., 1885, 

 p. 184. 



Hesione ehlersi, Gravier, Nouvelles Archives de Museum 

 Paris, 1900, p. 175. 



A comparison of the descriptions of the above species 

 inchnes me very strongly to the opinion that they are 

 synonymous. I can find no definite characters that serve to 

 distinguish the one from the other. True, one author gives 

 some detail that is not mentioned by another. In the case of 

 Savigny "s account, for example, an inspection of the figures 

 alone has led some authors to regard that species as blind 

 and as being without prostomial tentacles ; but, as Grube 

 has pointed out, these organs are mentioned in the diagnosis 

 of the genus Hesione on the previous page of the work, and 

 as this species is the type, eyes and tentacles must have been 

 present, though overlooked by the artist. Grube has also, 

 on more than one occasion, made it clear from a careful 

 perusal of the diagnosis and of the figures, that the species 

 has four pairs of peristomial cirri. I note that in the drawing, 

 too, the preanal cirri are not included, though reference is 

 made in the text to them. 



M'Intosh notes that his species is nearly allied to Savigny 's, 

 though the " body is more elongate and the shape of the 

 head is different." 



Grube^ writes of H. ceylonica: — "Species cum Hesione 

 splendida, Sav., maxirae congruens, sed dorso fuscius lineato, 

 haud transverse sulcatc, cirrisque teniae ularibus longioribus 

 differens,"and Willey^has that it "is probably a geographical 

 form of H. splendida." 



1. Grube— Proc. Zool. Soc. 1874, p. 327. 



2. Willey — Ceylon Pearl Oyster Fisheries, pt. iv., Suppl. Rep., xxx., 

 — Polychae'ta, 1905, p. 266. 



