Arenicola assimilis 123 



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

 very small example, 7 to 8 mm. long, which 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. 



DISTEIBUTION. A. pusilla is known to occur in Europe only at 

 Naples and at Ossero (on the Island of Cherso) in the Adriatic. 1 It 

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

 Mediterranean (see p. 93) relate to the present species. 



A. pusilla has been obtained at several stations on the western 

 seaboard of America, namely, the Aleutian Islands (Amchitka, Atka, 

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

 Humboldt Bay, Cal., and Coquimbo (Chile). Examples recorded 

 (under the name A. piscatorum) from the Bay of Paita, Peru, were 

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

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

 examples of A. pusilla 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 2 is unknown. 



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



Naples Ashworth Coll. 1912. 4. 9. 27. 



Dutch Harbour, Uualaska . 1912. 4. 9. 28. 



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



ARENICOLA ASSIMILIS Ehlers, and var. affinis Ashworth. 



Plate VII, Fig. 16 ; Plate X, Fig. 29 ; PL XIII, Fig. 45 ; 

 PL XIV, Fig. 50. 3 



Arenicola assimilis Ehlers. 



Arenicola assimilis, partim 



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

 Ges. 'NViss. Gottingen (1901), pp. 176, 177. 



1 Careful search for this species has been made at Palermo and near Messina, 

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

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

 bourhood. 



2 See remarks on a specimen from Siberia on p. 93. 



3 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. 



