722 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [24] 



The foot ends iu three rouuded lobes, of which the upper (fig. 45) is 

 very large, the two lower small and projecting beyond the upper, diver- 

 gent. The anterior feet are in length about one-half the width of the 

 body, growing progressively longer along the anterior third, from which 

 point their length equals the width of the segments to which they are 

 attached. 



The anal segment is about double the length of the segment preced- 

 ing it. There are three anal cirri ; the lateral cirri are made up of from 

 three to five nearly cylindrical articles, each one slightly less in diame- 

 ter than the one preceding it, and in length equal to the anal segment ; 

 the median cirrus is in all respects similar to the basal article of the 

 lateral. 



There are two kinds of setae in the upper bundle ; in the upper part 

 one to three very delicate capillary sette (fig. 40) minutely denticulated 

 along one edge for some distance ; below these, two or three having a 

 very peculiar form (fig. 47) ; these are about two-thirds as long as 

 the first form, inner three-fourths of uniform diameter, near the end 

 denticulated, external tooth sharp pointed, prolonged nearly in the line 

 of the main part of the seta ; external to the base of this tooth the seta 

 becomes suddenly very delicate, capillary. These setae may be curved, 

 as in the figure, or straight. In the lower bundle only compound setae 

 (fig. 48) are found. These are arranged in a fan, growing progressively 

 shorter from the upper to the lower j^art of the fan, the shortening, for 

 the most part, affecting the appendix. With such magnifying power as 

 we had the appendix of these setae seemed to have the apex bluntly 

 rounded, without tooth. 



The body was convex above and at the sides, flattened below ; the 

 segments distinctly separated from each other by well-impressed lines 

 of segmentation. 



The general color was white. 



Length of largest specimen, 8™™. 



Width, 0.5'""^. 



Number of segments, 51. 



In young specimens the antennae and palpi appear as mere buds. The 

 head is larger relatively than in adults. The dorsal cirri have no basal 

 articles, but arise, like the ventral cirri in mature forms, from the side 

 of the foot, near the end. They moved with a j^erfectly uniform gliding 

 motion, due, no doubt, to the action of cilia, without any apparent effort 

 of the body or feet. In a more advanced stage the palpi were club- 

 shaped, lacking the terminal article. 



Very common in sand at low water. The young forms were especially 

 numerous. 



