NO. 1772. ANNELIDS OF THE ARENICOLID.^—ASHWORTH. 17 



the Puget Sound specimens and those from Naples are the vastly 

 greater size — at least eight times as great — of the former and the 

 smaller number of oesophageal coeca or pouches in the latter." 

 The difference in regard to the number of oesophageal coeca in speci- 

 mens from Naples and the western seaboard of America seems to be a 

 clear one, and is sometimes even striking. Neapolitan specimens 

 seldom have more than four pairs of coeca, but I have seen only one 

 American example with as few as five pairs; the others had six, eight, 

 nine, and ten pairs, and Johnson records specimens with fifteen 

 and sixteen pairs, and one with sixteen coeca on the right and eighteen 

 on the left side. Johnson's remark regarding the comparative size of 

 Neapolitan and American specimens is not in agreement with my 

 experience; possibly he had been supplied with very small Neapolitan 

 examples. There is not so great a difference in the length of 

 specimens from the two regions. I have seen sixteen specimens 

 from Puget Sound, including four from Johnson's collection, the 

 largest of which is 103 mm. long (of which the tail forms 28 mm.), 

 and 11 of them are less than 50 mm. long. I have recently had a 

 Neapolitan example 97 mm. long (of which the tail forms 20 mm.), 

 and the average length of nine specimens which have just passed 

 through my hands is 80 mm. (of which the tail forms 17 mm.). Lo 

 Bianco states that examples of this species from the Bay of Naples 

 attain a length of 150 mm." The longest American specimen of 

 A. claparedii I have seen is one from Crescent City, California, in the 

 Harvard collection, which is 207 mm. long, but this great length is 

 largely accounted for by the unusual extent of the tail, which meas- 

 ures no less than 117 mm. American specimens have generally a 

 thicker body wall than Neapolitan ones, and are stouter; among the 

 scores of living and preserved Neapolitan examples of this species 

 which I have examined I never saw any whose girth approached 

 that of the massive specimens from Unalaska. (See p. 13.) 



Summary of the distribution of Arenicola claparedii on American 

 shores. — Arenicola claparedii is now known from several stations on the 

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

 Atka, Unalaska), Vancouver Island, San Juan Island, Puget Sound, 

 Crescent City and Humboldt Bay, California; Coquimbo and Puerto 

 Montt (Chile). 



Further distribution. — Naples, Ossero (Adriatic), Angra Pequena 

 (southwest Africa), and North Japan. 



ARENICOLA ASSIMILIS Ehlers. 



Twenty chaetigerous segments; thirteen pairs of gills, the first, 

 which is on the eighth segment, may be small or absent; the gills may 

 be bushy or may tend toward the pinnate type, but are seldom 

 clearly and typically pinnate; median lobe of the prostomium 



a Atti R. Accad. Sc. fis. mat., Napoli, vol. 5, ser. 2, 1893, no, 11, p. 9. 

 Proc.N.M.vol.39— 10 2 



