36 THE ANNELIDA POLYCHAETA. 



and probably others, Harmothoe lunulata also occurring on the latter) ; ophiurans 

 {e.g., Scalisetosus communis on Ophiothrix alopecurus Miiller & Troschel and 0. 

 fragilis (Abild.)); sea-urchins (e.g., Scalisetosus echini on Echinus esculentus 

 Linne to which it presents a clearly mimetic resemblance and Hololepidella 

 commensalis Willey on Clypeaster humilis Ceylon pearl oyster fisheries report, 

 1905, pt. 4, p. 251); holothurians {e.g., Lepidasthenia pulchra Johnston on 

 Stichopus calif ornicus (Stimpson) which it matches in color); molluscs {e.g., 

 this same Lepidasthenia pulchra occurring in the cavity between mantle and 

 foot in Lucapina crenulata); other annelids, this group and that of the echino- 

 derms being the ones which bear polynoids in greatest numbers, these having 

 been noted in association with serpulids, terebellids, arenicolids, chaetopterids, 

 cirratulids and even eunicids, an interesting case being that noted by Webster 

 in which Harmothoe parasitica lives under the elytra of Lepidametria commen- 

 salis which in turn is itself parasitic on Amphitrite ornata (Trans. Albany insti- 

 tute, 1879, p. 9) ; Enteropneusta {Lepidasthenia digueti Gravier in association 

 with a Balanoglossus from the Gulf of California cf. Gravier, Bull. Soc. philom., 

 1905, ser. 9, 7, pt. 3, p. 160) ; and tunicates {e.g., Herdmanella ascidioides Mcin- 

 tosh), in the branchial chamber of an ascidian, probably a Styela, see Darboux, 

 Bull. sci. France & Belgique, 1900, 30, p. 11, etc.). 



As with the aphroditids, the polynoids frequently themselves bear various 

 other animals, including protozoans, sponges, coelenterates, bryozoans, other 

 annelids, and Crustacea, some members of which seem to be the parasites most 

 common {e.g., species of Selius, Silenium, and Selioides, see St. Joseph, Ann. 

 sci. nat., 1888, ser. 7, 5, p. 141). 



Like other aphroditoids, the polynoids are carnivorous, feeding upon such 

 forms as sponges, hydroids, other annelids and crustaceans and more rarely 

 small molluscs. 



Of very great interest in the present Albatross collection are the pelagic 

 members of the Polynoidae which add four species, including three new genera, 

 to the six species previously known. The ten forms are as follows: — 



1. Polynoe pelagica Viguier Arch. zool. exper., 1886, ser. 2, 4, p. 416. Medi- 

 terranean. 



2. Polynoe innatans, sp. nov. Eastern south Pacific. 



3. Nectochaeta grimaldi Marenzeller, Bull. Soc. zool. France, 1892, 17, 

 p. 183. North Atlantic. 



4. Harmopsides natans, gen. et sp. nov. Coast of Peru and at several 

 stations northward to the latitude of Central America. 



