ADDITION TO POLYCHAETOUS ANNELIDS 



191 



This differs from other genera in that it has only one row of 

 paleae, the place of the inner row being taken by the V-shaped ar- 

 rangement of hooks. 



Genotype. — Monorchos philippinensis, new species. 



MONORCHOS PHILIPPINENSIS, new species 



Figures IS to 20. 



A number of individuals were collected at D 5526, between Siquijor 

 and Bohol Islands, 9° 12' 45" N., 123° 45' 30" E., August 10, 1909, 



Figs. 13 to 20, Nereis masalacbnsis Grdbe. 13, prostomium X 20 ; 14, third para- 

 podicm of male X 45 ; 15, tenth parapodium of male X 45 ; 16, modified para- 

 podium x 45; 17, apex of compound seta X 250. Monorchos philippinensis, 

 new species. 18, anterior end X 2.5 ; 19, thoracic setae X 45 ; 20, uncinus 

 X 185. 



805 fathoms, (one, the holotype, bears Cat. No. 1920 F, U.S.N.M.). 

 Although none retained more than the anterior regions of the body, 

 these are so characteristically different from other genera in this 

 family that the formation of a new genus seems necessary. 



The type of the species measures 25 mm. from the anterior end 

 of the operculum to the beginning of the uncinigerous tori and has 

 an opercular width of 6 mm. Except for the median ventral in- 

 cision, the opercular lobes are completely fused, and their dorsal 

 surfaces are smooth except for indistinct ridges starting from the 



