AMPHICTEIS OBSCURIOR. 447 



teeth and at one end the usual rounded prominence, between which and the 

 teeth there is a small subnodular tooth, or process. The nonserrate margin is 

 somewhat convex and projects in a prominent angular shoulder well toward the 

 end opposite that on which occurs the rounded prominence of the opposite side. 

 The uncinus is clearly cross-striate. (Plate 77, fig. 7). 



Locality. Gulf of Cahfornia: Sta. 3435 (lat. 26° 48' N., long. 110° 45' 

 20" W.). Depth 859 fms. Bottom of brown mud with black specks. Bottom 

 temp. 37.3° F. 22 April, 1891. One specimen. 



A number of broken tubes apparently pertaining to this species were taken 

 with the specimen. They are thick walled, of varying diameter, and composed 

 of fine brownish mud. 



Amphicteis Grube. 



Archiv naturges., 1851, 17, p. 82; 1860, 26, p. 103. 



Crossosioma Gosse, Ann. niaj?. nat. hist., 1855, ser. 2, 16, p. 310. 



Amphicteis obscurior, sp. nov. ^ 

 Plate 76, fig. 1, 2; Plate 77, fig. 3. 



Color above, black of bluish cast, below, more greyish black in the anterior 

 region and bluish black posteriorly. Setae pale, in one paratype of dilute 

 bronze cast, but not at all yellow or golden. 



Greatest width, 5 mm., this being at the fifth and sixth setigerous somites. 



Prostomium narrowed cephalad, the anterior margin incised at middle 

 a,nd convex on each side adjacent to the incision, straight ectad. At the base 

 above strongly elevated, the elevated portion rounded and marked with a short 

 median longitudinal sulcus. In front of the elevated region and near the middle 

 of the length of the lobe it is strongly depressed transversely. A median longi- 

 tudinal furrow extending caudad from the anterior notch to the transverse 

 depression, where it is bifurcate. (Plate 76, fig. 1, 2). 



The peristomium presents a large well-defined lower Up. This is subtrapezi- 

 form in outline, but with the narrower anterior edge moderately convex and the 

 anterior corners well rounded. A little back of the middle is a transverse sulcus 

 which bows forward convexly at the middle and sends a short branch caudo- 

 mesad on each side of the beginning of the convexity. There is a dark trans- 

 verse stripe across the middle of the part of the lip in front of the sulcus, and in 



1 obscurus, dark. 



