12 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 39. 



pairs of nephridia which open on the fifth to the ninth segments'*; 

 several (four to sixteen) pairs of (Esophageal glands, the anterior pair 

 long and slender, the others shorter and more or less pear-shaped; 

 no pouches on the first septum; statocysts absent. This last is a 

 most noteworthy feature, and is diagnostic of the species, for all 

 other known species of Arenicola possess statocysts. 



This species has been hitherto re- 

 corded from only three stations on the 

 American coast, namely: 



A. claparedii, Crescent City, California. F. 

 W. Gamble, and J. H. Ashworth. Quart. 

 Journ. Micr. Sci., vol. 43, 1900, p. 423. 



A. claparedii, Crescent City, California. J. H. 

 Ashworth, Quart. Journ. Micr. Sci., vol. 46, 

 1903, pp. 773-774. 



A.daparedei, Puget Sound, ^ Washington. H. 

 P. Johnson, Proc. Boston. Soc. Nat. Hist., vol. 

 29, p. 421, 1901. 



A. claparedii, Puget Sound, Washington. J. 

 H. Ashworth, Quart. Journ. Micr. Sci., vol. 46, 

 1903, p. 774. 



A. claparedii, c Falkland Islands. E. M. 

 Pratt, Mem. Proc. Manchester Lit. Philos. Soc, 

 vol. 45, no. 13, p. 12; no. 14, p. 15, 1901. 



A. claparadii,c Falkland Islands. R. Val- 

 LENTiN, Mem. Proc. Manchester Lit. Philos. 

 Soc, vol. 48, no. 23, p. 9, 1904. 



The records from Crescent City and Puget Sound hold good, but 

 those from the Falkland Islands must be transferred to the species 

 A. assimilis. Miss Pratt's record is founded on certain post-larval 

 specimens of Arenicola taken by Mr. Vallentin in Stanley Harbor. 

 These post-larval specimens were subsequently re-examined, two of 

 them were sectioned, with the result that they were conclusively 

 shown to be young stages of A. assimilis, var. affinis.^ Mr. Vallen- 

 tin's record is undoubtedly based on Miss Pratt's. All the specimens 

 of Arenicola which he collected in the Falkland Islands were examined 

 by me and it was from them that I described the new variety affinis of 

 A. assimilis in the paper cited'* (pp. 768-772), All the specimens belong 

 to this variety; there is no example of A. claparedii among them. 



The specimens, five in number, from Crescent City, are in the 

 Museum of Comparative Zoology, Cambridge, Massachusetts (register 



a Out of 100 specimens examined I have seen only three which depart from this con- 

 dition; in each of these there was also a nephridium opening on the fourth segment. 

 These three specimens were from the west coast of South America, namely, from Co- 

 quimbo ("J., pusilla" Quatrefages) and from Puerto Montt, Chile. See also p. 16. 



b This species was also obtained in Puget Sound by C. M. Child, but was erroneously 

 stated to be A. marina. (Trans. N. Y. Acad. Sci., vol. 16, 1898, p. 387.) See p. 8. 



<^ A. assimilis, var. affinis. See the lower part of this page. 



dj. H. Ashworth, Quart. Journ. Micr. Sci., vol. 46, 1903, pp. 764-768. 



Fig. 2.— a. CLAPAREDn, antekioe end, 



DORSAL ASPECT OF SPECIMEN FROM CRES- 

 CENT CITY, CALIFORNIA, TO SHOW THE 

 PROSTOMIUM. L, LATERAL LOBE OF PRO- 



stomium; JW", MEDIAN lobe; JI/o, mouth; 

 N^, first notopodium. X6. 



