PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 80 



EUPOMATUS DKCORLfS, new species 



FiGUHE 3 



An average-sized specimen has a length of 18 mm. from the collar 

 margin to the end of the pygidium and a width at the collar margin 

 of 1.5 mm. The branchial filaments are about 18 on a side, their 

 length in a well-expanded specimen being 3 mm. The operculum 

 and its stalk are large as compared with the filaments and extend 

 considerably beyond them. In the 11 specimens in the collection, 5 

 have the operculum on the left side with a small and inconspicuous 

 pseudoperculum on the right. In five others these relations are 

 reversed, and in one there is a fully developed operculum on either 



side. The radioles are very short at the 

 base of the branchia but soon become 

 longer and at the end have a length foui' 

 times the diameter of the branchia. 

 There is a smooth tip, as long as the 

 longest radiole, at the end of each 

 branchia. The operculum stalk broadens 

 into a funnel, which carries approxi- 

 mately 40 teeth on its margin. The ter- 

 minal hooks on the operculum are 12 in 

 number, long, slender, and gently curv- 

 ing to very sharp points. 



The branchia arise from a conmion 

 base, which is about as high as the collar. 

 The collar has four lobes, the doi'sal 

 ones at their dorsal ends overlapping the 

 bases of the opercular stalks and sepa- 

 rated from one another by a considerable 

 space. A deep depression on each side 

 separates the dorsal from the ventral 

 lobe of the collar, the two latter ones 

 overlapping on the ventral surface and 

 extending farther over the bases of the gills than do the dorsal. 

 The fii-st seta tuft lies in the dorsal collar lobe. 



In preserved material the general body color is pale straw, marked 

 as follows with dark-brown pigment : A median stripe in each ter- 

 minal tooth of the opercular margin ; a narrow band on each side of 

 the opercular spine, in some cases spread more diffusely over the base 

 of the spine ; a heavy band on the ventral surface, covering each torus 

 of the last six thoracic somites; and a very much narrower band on 

 the ventral margin of each abdominal somite, marking the region of 

 the torus with a minute but still prominent spot at the location of 

 the seta tuft. 



/ 



ic 



b 



Figure 3. — Evpomatus decorus, 

 new species : a. Dorsal abdom- 

 inal seta, X 250 ; h, stout seta 

 from first bundle, X 165 ; c, dor- 

 sal tlioracic seta, X 250 ; d, 

 uncinus. X 250 



