

136 THE VOYAGE OF H.M.S. CHALLENGER. 



6. Nogagus murrayi, n. sp. (PL LV. fig. 1). 



Length, 16-100ths of an inch (4 mm.). Cephalothorax ovate, much longer than 

 broad, and nearly thrice as long as the abdomen ; frontal margin rounded, lateral margins 

 somewhat sinuous, posterior angles moderately produced backwards and rounded off. 

 First abdominal (genital) segment about as long as broad, margins round ; angles not 

 at all produced nor acute. Two posterior abdominal segments much broader than long, 

 the last pentagonal in shape, and produced backwards between the caudal lamellae into two 

 obtuse points ; caudal lamellae about as broad as long, subquadrate, each bearing four 

 finely plumose setae. 



Taken in the open sea off Eio de Janeiro, and in the North Atlantic (about lat. 25° N.), 

 April 28, 29, 1876. Very similar to Nogagus errans. Kroyer, which, however, differs 

 decidedly in the shape of the last abdominal and two posterior thoracic segments. 



Family II. Dichelestid^. 



Hessella, 1 n. gen. 



Body much elongated, cylindrical ; cephalothorax not much more tumid but longer 

 than the abdomen, which terminates in two blunt adpressed lobes, each bearing three 

 small setae. Anterior antennae very small, indistinctly five-jointed (PI. LV. fig. 10), 

 and densely setose; posterior (fig. 11) small, but stout and hamate. Four pairs of 

 swimming feet, the branches all Inarticulate, first and second pairs (fig. 12) two- 

 branched, third and fourth (fig. 13) one-branched. 



Hessella cylindrica, n. sp. (PI. LV. figs. 9-13). 



One specimen only taken off Zamboanga, 



The species most nearly approaching this seems to be Clavella tenuis, Heller, the 

 general characters of some of the appendages being very similar to those of Hessella; 

 but the proportions of head, thorax,, and abdomen are widely different, as also are the 

 antennae. I was unable to find any mouth-organs. 



Family III. Chondracanthid.e. 



Chondracanthus, De la Roche. 



Two pairs of foot-jaws, prehensile, the third nearly rudimentary. Appendages of 

 thorax representing the feet, in form digitated, but not articulated, and not setiferous 

 lobes or tubercles, oviferous tubes very short, broad and flattened (Baird). 



1 Named after M. Less? ol Fiest, author of numerous memoiis on vansi ic Crastrc?a. 



