Arenicola assiinilis 123 



The writer found, in mud dredged near Naples (IMay 15, 1900), a 

 very small example, 7 to 8 mm. long, wliicli already possessed the 

 full number of branched gills and four pairs of oesophageal caeca. 

 The nephridia had also assumed practically the adult form, but the 

 "prostomium was in a transitional condition. 



Distribution, — A. puslUa is known to occur in Europe only at 

 Naples and at Ossero (on the Island of Cherso) in the Adriatic.^ It 

 is possible that some of the records credited to A. marina from the 

 ]\Iediterranean (see p. 9.S) relate to the present species. 



A. pusil/a has been obtained at several stations on the western 

 seal)oard of America, namely, the Aleutian Islands (Amchitka, Atka, 

 Unalaska), Vancouver Island, Puget Sound, Crescent City and 

 Huml)oklt Bay, Cal., and Coquimbo (Chile). Examples recorded 

 (under tlie luime A. piscatonim) from the Bay of I'aita, Per\i, were 

 probably A. pusilla, and two specimens from Puerto Montt, Cliile, 

 are placed provisionally in this species. The writer has seen two 

 examples of A. imsilla from North Japan. 



The records suggest that this species is present generally on the 

 shores of the North Pacific, and that it extends well down the west 

 coast of South America. How far the species extends into the 

 Behring Sea and along the Coast of Siberia - is unknown. 



Type specimen in the Museum d'Histoire Naturelle, Paris. 



Naples Ashwovtli Coll. 1912. 4. 9. 27. 



Dutch Harbour, Unalaska . . „ „ 1912. 4. 9. 28. 



San Juan Island, Puget Sound . „ ,, 1912, 4. 9. 29. 



Arp]NICOLA assimilis Elders, and var. affinis Ashworth. 



Plate VII, Fig. 16 ; Plate X, Fig. 29 ; PI. XIII, Fig. -ir> ; 

 PI. XIV, Fig. 50.^^ 



Arenicola assintili.'^ Ehlers. 



Arenicola assimilis, _2Jfl/7i»( — 



Killers, Polych., in Hamb. Mag. Samnielr., ii, 1 (1897), p, 103; Fests, K. 

 Ges. "\Viss. Gottingen (1901), pp. 176. 177. 



' Careful search for this species has been made at Palenno and near Messina, 

 but without success. Prof. C. Viguier, Director of the Zoological Station, 

 Algiers, has infonued the writer that he has not seen Arenicola in that neigh- 

 bourhood. 



* See i-emarks on a specimen from Siberia on p, 93, 



•'' For other figures of this species, see Figs, 14, 22, pp, 46, 51, chaetae of 

 adult ; Fig. 21, p, 50, crotchets of post-larva ; Fig, 38, p, 68, statocysts. 



