28 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 39. 



The notopodia are simple conical elevations which call for no com- 

 ment, except that in some of the segments they are retracted, in 

 which case the setae appear to issue from a slit on the body wall. 

 (See fig. 12, N.^) 



Specimen No. 1 presents an interesting abnormality. There is, on 

 both sides, an eighteenth neuropodium, about the same size as the 

 seventeenth, but there is no corresponding notopodium or gill. I 

 have met with a similar abnormality in several other species of Areni- 

 cola, but it is by no means frequent. 



The tail, in those specimens in which it is preserved extended, is 

 encircled by pale grooves, which are more strongly marked at seg- 

 mental intervals. In No. 2 about 22 segments are so indicated; in 

 No. 6, 14 segments; and in No. 7, 21 segments. In No. 1 the tail is 

 contracted and its markings are not clear. The papillse on the tail 

 are feebly developed and there are no longer processes present such 

 as are found in the tail of A. cristata. 



Setse. — Most of the notopodial setae are imperfect, their tips having 

 been broken off, but two or three perfect ones have been examined. 

 These are of the same type as those of A. marina; they are about 

 3.3 mm. long and taper to a fine point and their terminal third bears 

 numerous minute pointed processes closely appressed to the shaft of 

 the seta. No setae bearing a laminate margin were observed. 



Three series of neuropodial crotchets from different specimens 

 (Nos. 3, 6, and 7) have been examined. Most of these crotchets are 

 similar to those of examples of A. marina about 70 to 100 mm. in 

 length. The shaft of the crotchet is curved, but not strongly so, 

 and it presents only a slight dilatation near the middle of its length. 

 The distal portion forms a beak-like structure, the "rostrum," bent 

 at an angle of about 130° to the shaft. Immediately proximal to 

 the rostrum, on the convex side of the crotchet, there is occasionally 

 a minute tooth, or sometimes two, to be seen, but in most cases 

 teeth are wanting. Only a few of the crotchets examined have a 

 sub-rostral tooth and when present it is very minute. In most of the 

 crotchets the rostrum is a bluntly conical beak, but in one of the 

 series, which contains the longest crotchets, the rostrum is longer, 

 curved and almost scythe-like in shape (fig. 14, D). This differ- 

 ence is probably attributable to the greater age of these crotchets. 

 The most interesting point observed during the examination of 

 the neuropodial crotchets was in the series from No. 6. At 

 the base of the crotchets in use (fig. 14, B), which are about 

 0.2 to 0.25 mm. long, there are two much smaller, more strongly 

 curved and only about 0.13 mm. long, so that their tips would 

 not project beyond the lips of the neuropodial groove (fig. 14, 

 A). These small crotchets have a comparatively larger distal re- 

 gion and well-marked teeth are present behind the rostrum. The 



