ONUPHIS COBRA. 305 



paler. On the ventral surface the glandular areas along each side are paler, 

 as usual, as are also a number of infraganglionic spots along the midventral line. 



The tubes consist of a thin lining membrane with a thick coat of fine, dark 

 greenish grey mud, in which are numerous Globigerina shells, etc. The longest 

 tube, apparently incomplete, is 22 mm. long and has a maximum external diame- 

 ter of 8 mm. The smallest tube has a diameter of 5 mm. One tube has 

 attached to it a piece of decaying wood. 



Locality. Off Panama: Sta. 3381 (lat. 4° 56' N., long. 80° 52' 30" W.). 

 Depth 1,772 fms. Bottom of green mud. Bottom temp. 35.8° F. 6 March, 

 1891. Two specimens and several tubes. 



This species is close in its general structure to hiatidentata Moore and to 

 crassisetosa, sp. nov. From both these species it differs in form and proportions 

 and in having the branchiae much shorter, these being always much exceeded 

 by the notocirri, which are unusually large, as if in compensation for the shorter 

 cirri, as well as in having the branchiae all conspicuously flattened. From 

 hiatidentata it differs in ha\'ing the branchiae begin on the fourteenth parapodia 

 instead of on the thirteenth; decidedly in the triangular form of the carrier of 

 maxillae I, and in the number and form of the teeth of the other maxillae. The 

 ceratophores of the tentacles are proportionately more slender. From crassisetosa 

 it differs in being decidedly larger, the diameter being 4 mm. as against 2 nam., 

 and in presenting a conspicuously widened region back of the narrow anterior 

 end. The first metastomial somite is decidedly shorter in comparison with the 

 peristomium. In the maxillae the carrier of I differs in being strongly narrowed 

 caudad; the distal tooth of the outer left plate of II is proportionately much 

 smaller, and its teeth number ten instead of but seven, the inner plate being also 

 ten as against eight, while the right plate has eleven as against nine, the teeth 

 differing in form as well. The pectinate setae resemble those of crassisetosa 

 in ha\dng the reflexed angles at the distal end, but these are smaller and less 

 conspicuous. The setae of the first parapodia differ in being apparently un- 

 join+ed. The tube of the present species is of mud over a thin lining membrane, 

 whereas in crassisetosa the tube is simply hyaline without foreign adherent 

 material. 



