NO. 1772. ANNELIDS OF THE ARENICOLIDJE—ASHWORTH. 7 



described; uo single character is mentioned by means of wliich the 

 species with which Girard was deaHng can be absokitely fixed. Never- 

 theless, it is, I consider, practically certain that the specimens in 

 question were ordinary examples of A. marina. It is evident from 

 the description that Girard mistook the ventral for the dorsal surface, 

 for he speaks of the dorsal region as being marked by a conspicuous 

 smooth line, which, upon the cephalic region, subdivides into right 

 and left branches, which unite again anteriorly; this dorsal line is 

 given as one of the principal specific features. This smooth band or 

 line is, however, really ventral in position, and is seen in nearly all 

 specimens of A. marina (and, indeed, in other caudate Arenicolidse) ; 

 it marks the position of the ventral nerve cord, and in front it is con- 

 tinuous with the metastomial grooves, which mark the course of the 

 oesophageal connectives. I have endeavored to procure the type- 

 specimen of this species, but without success; the curator of the 

 museum of the Boston Society of Natural History informs me (letter 

 dated, November 4, 1908) that he has not been able to locate the type 

 and that there is no record of its having been given to the Society. 

 There can be little doubt that the specimens were examples of A. 

 marina, which species, as may be seen from the list of records given 

 above, has been found at other stations in the immediate neighbor- 

 hood of Chelsea. 



There are two specimens in the Museum of Comparative Zoology, 

 Cambridge, Massachusetts, which were collected at Grand Manan 

 and bear the label "Arenicola natalis Girard." (Mus. No. 87.) I have 

 re-examined these and have no hesitation in referring them to the 

 species A. marina, with which they agree in every respect, both in 

 regard to external characters and internal organs. 



The records from Vancouver Island, Puget Sound, the Bay of 

 Paita, Callao, and Puerto Montt can not be passed without emen- 

 dation. 



Von Marenzeller*^ states that he examined examples of A. marina 

 from Vancouver Island. As his diagnosis was reached from a con- 

 sideration of the external characters only it seemed to me that a 

 re-examination, which should include the internal organs, was desir- 

 able. Professor von Marenzeller kindly lent me a specimen for this 

 purpose. The specimen is about 70 mm. long and looks at first 

 sight like a small example of A. marina, except that the lateral lobes 

 of its prostomium are proportionately larger than those of A. marina. 

 Although I had a suspicion that it should not be referred to this 

 species, it was impossible to finally determine this point by an 

 examination of the external features only. Accordingly, an incision 

 was made along the greater part of the worm and the flaps of the body 

 wall turned aside. It was then seen that instead of a single pair of 



oZool. Jahrb. Abth. Syst., vol. 3, 1888, p. 12. 



