86 



PROCEEDINGS OF THE ACADEMY OF 



[Feb., 



assumes in crawling about over the sea- 

 weeds on which it is commonly found. 

 The outlines of the example from 

 which fig. 1, PI. XII, was taken repre- 

 sent the animal in a somewhat greater 

 state of extension, showing especially 

 well the form of the last segment and 

 the caudal appendage. The head is 

 bluntly conical or rounded in front, 

 and narrows posteriorly to a somewhat 

 constricted neck, where it joins the 

 trunk. Its dorsal surface is also 

 rounded, and bears a pair of reddish 

 eyes, reniform in shape, as is usual in 

 this group. On its ventral surface the 

 head is slightly flattened. The trunk 

 is long fusiform, or cigar-shaped, taper- 

 ing toward the posterior end, and di- 

 vided by six constrictions into as many 

 segments.^ The first two segments are 

 very short, scarcelj" equal to the head 

 in diameter and are limited by relatively 

 deep and well-m.arked constrictions. 

 The three succeeding segments are sub- 

 equal, nearly as broad as long, and sep- 

 arated by comparatively slight con- 

 strictions. In the first of the segments 

 last descriljed, namely, the third of the 

 trunk, the latter reaches its greatest 

 diameter. The sixth segment is short 

 and rounded at its posterior end, and 

 bears on its ventro-posterior surface the 

 conical caudal appendage or tail, which 

 in this species is unsegmented. 



Like other members of the group, D. 

 conkiiiii is encircled by a number of 

 bands or rings of cilia, and also possesses the usual ciliated tracts 



Fii;-. I.— Female individual of 

 1). conkiiiii, drawn from a 

 fixed and mounted specimen. 

 Details added from sketches 

 of living animals. (X 142.) 



1 In the descriptive portion of this paper the term "segment" will be used to 

 designate a portion of the trunk bounded by constrictions, without reference to 

 the question whether it is a true metamere. The problem of metamerism in 

 Dinophilus is discussed in Section III, 7. 



