94 THE ANNELIDA POLYCHAETA. 



Nepthys ectopa, sp. nov.^ 

 Plate 15, fig. 1-7. 



The general color is light brown without distinct markings excepting a 

 short median longitudinal dark line extending caudad on the dorsum from the 

 caudal angle of the prostomium, and a dark band in the median ventral furrow 

 which at the anterior end is Y-shaped. 



The type, which lacks the posterior region, is composed of forty-eight 

 somites. It has a total length, exclusive of the proboscis, of near 27 mm. and 

 a maximum width of 3 mm. The body is clearly widest at the anterior end 

 (at the 5th or 6th somite), narrows strongly to about the twelfth somite, and 

 then more gradually caudad. 



The prostomium is in the form of a broadly subtriangular plate with base 

 cephalad, the apex of which extends back to the fourth somite and thus divides 

 above the first three somites. The anterior margin is straight or very slightly 

 concave between the widely separated lateral corners which bend back obliquely 

 caudad. The anterior border slopes ventrocephalad. Surface in general 

 smooth and shining. Close to each lateral margin and about midway of the 

 length is a convex elevation, subelliptic in outline, which apparently represents 

 an eye though wholly without dark pigment at present. On the anterior 

 margin are two pairs of short, colorless and conical processes or tentacles; on 

 each side there is one on the oblique line of the corner and one at the end of the 

 straight median region close to the first one, the two on each side being thus 

 widely separated from the two on the other. (Plate 15, fig. 1). 



What is interpreted as the peristomium appears on the ventral side as a 

 straightly margined, narrow band weakly divided by a transverse furrow; it 

 extends up each side and disappears beneath the border of the first setigerous 

 somite before reaching the prostomium, which thus appears to be wholly free 

 from it. It bears no cirri. 



The first two setigerous somites are evident only dorsally on each side of 

 the prostomium. On e ach side these somites lie between the prostomium and 

 the third setigerous somite, against which these outer ends lie. Each bears 

 only a fully developed notopodium, the neuropodium being wholly absent. 

 The fourth somite (third setigerous) extends farther ventrad than the two 

 preceding but is likewise incomplete beneath, while above it is partly separated 



' tKTOTTos, strange. 



