136 THE ANNELIDA POLYCHAETA. 



Tissue of body dense, opaque, and well pigmented. 



Pelagic in habits. 



Genotype. — Mauita nans, sp. nov. 



This genus seems undoubtedly nearest to Vanadis Claparede. It is sepa- 

 rated from that form because of the reduction of the first somite and its seem- 

 ingly complete fusion with somite II. This reduction and fusion gives a very 

 different appearance in ventral view. The strong development of the para- 

 podia is a conspicuous feature. 



Mauita nans, sp. nov. 

 Plate 24, fig. 10, 11; Plate 25, fig. 1-6. 



No complete specimen is represented in the collection. An anterior frag- 

 ment consisting of head and sixty-seven somites is 45 mm. long, with a maximum 

 width, exclusive of the parapodia, of 3.25 mm., inclusive of the parapodia, of 5.5 

 nam., and to the tips of the setae near 8.3 mm. The width of the head across 

 eyes is 3 mm. A fragment, lacking the head and caudal end, 64 mm. long, con- 

 sists of seventy-seven somites; and a second similar fragment of the same length, 

 but more slender, consists of one hundred and two somites. 



The eyes are large and protruding, as usual, making up the principal bulk 

 of the prostomium. The corneal surface of each is more convex and is directed 

 outward and very sightly cephaloventrad. The caudal region of the prostom- 

 ium between the eyes is elevated, forming a thick transverse ridge or isthmus 

 between the eyes. In front of this isthmus the dorsal surface is abruptly and 

 deeply depressed, and then maintains the same horizontal level to the anterior 

 border, which extends straight across between the anterior edges of the eyes. 

 From the caudal region of the depressed area a short rounded process, the median 

 tentacle, projects forward; from its base a somewhat elevated, superficially 

 flattened band, separated distinctly from the region each side, extends forward 

 along the median line, bending about the anterior end and continuing back 

 caudad along the ventral surface of the prostomium, this band narrowest across 

 the anterior surface, and widening caudad both on the dorsal and on the ventral 

 surface. The paired tentacles are invisible from above, being situated on the 

 ventral surface and well removed from the anterior edge. They are small, short, 

 and subconical. The posterior ones are decidedly closer together than the 

 anterior ones, the bases of the four outlining a trapeziform area. Caudally 

 the ventral surface of the head between the eyes is deeply depressed or excavated, 

 f Plate 25, fig. 3). 



