NO. 1772. ANNELIDS OF THE ARENICOLID.E—ASIIWORTH. 23 



I have recently examined specimens from the stations given below; 

 to those in the Smithsonian collection the register numbers are 

 affixed: 



Beaufort, North Carolina. [149, 4861, 42896.] 



Florida. [211.] 



Key West, Florida. [453 1 .] 



Pensacola, Florida. [27229.] 



Bermuda. [34478.] 



Curasao. [3798.] 



San Pedro, California. 



Monterey Bay, Cahfornia, 

 The specimen recorded from Pensacola, Florida, extends the 

 distribution of this species westward along the coast of Florida to its 

 extreme western Hmit. The one from Curasao is the first example 

 to be recorded from the coast of South America. Of special interest 

 is the finding of this species on the western seaboard of America, 

 which greatly extends its known range, for this species has hitherto 

 been found only at Naples, on the eastern coast of the United States 

 from Woods Hole southward, in Bermuda, and in the West Indies. 

 In one of the specimens from San Pedro there is a small gill on the 

 right side of the sixth segment. This is the only specimen of Arenicola, 

 out of thousands examined, in which I have seen a gill on the sixth 

 segment. 



Arenicola cristata is a giant among Polychaeta. One of the 

 examples from Beaufort has a length of 385 mm. (of which the tail 

 forms 115 mm.) and the specimen from Pensacola reaches a length 

 of 460 mm. (of which the incomplete tail forms 80 mm.) and its girth 

 at the sixth segment is about 60 mm. The largest example of this 

 species which I have had is one from Woods Hole, which attains the 

 great length of 515 mm. (of which the tail is 190 mm.) and a girth 

 of 75 mm. 



In this, as in other caudate species of Arenicola, the tail is obscurely 

 segmented, at segmental intervals there is a larger annulus and upon 

 this, in most American examples, there are, on the ventro-lateral or 

 lateral region, hollow outgrowths of the body wall usually in the form 

 of thumb-shaped processes. The processes at the base of the tail, i. e., 

 in the first tail segment, are usually the largest, and occasionally one 

 of them, generally the most dorsal one, is branched at its distal end, 

 resembhng a small gill; this branched process corresponds in position, 

 and seems to be serially homologous, with the gills on the preceding 

 segments. Neapolitan examples of this species do not possess these 

 long caudal processes; slightly larger epidermal papillae are present on 

 the larger annulus of each tail segment, but they are of the same order 

 as the papillse of the other annuli. 



