458 
THE VOYAGE OF H.M.S. CHALLENGER. 
The anterior uncinigerous processes are somewhat shorter than in Pista cristata. The 
hooks (PI. XXVIIa. fig. 35) present a small projection above the long posterior process, 
and the anterior angle is much more produced than in Pista mirahilis or Pista cristata. 
The posterior long process is proportionally larger than in Pista mirahilis. The posterior 
projection in these hooks seems to be the heel, the hollow beneath being due to the mode 
of attachment of the base of the long process. The ventral edge or base of the hook is 
slightly roughened. 
The somewhat coarse sand in the intestine presented a few Diatoms and sponge-spicules. 
The Pista intermedia of Webster and Benedict ^ is a closely allied form, the hooks, 
indeed, j^resenting only slight differences. 
Eupista, n. gen. 
Eupista dariumi, n. sp. (PI. L. figs. 2, 3 ; PL XXVIIa. figs. 30, 31). 
Habitat. — Trawled at Station 298 (off the west coast of America, south of Valparaiso), 
November 17, 1875; lat. 34° 7 ' S., long. 73° 56' W. ; depth, 2225 fathoms; bottom- 
temperature 35° '6, surface temperature 59°'0 ; sea-bottom, blue mud. 
About the average size of Pista cristata. Though considerable care has been 
exercised, the specimens are somewhat softened, the dense tubes of mud plugged by 
the animals being nnfavonrable for the percolation of the spirit. 
In the general form of the body this species agrees with Pista. The cephalic lobe is 
furnished anteriorly with numerous sulcate tentacles. No ocular specks are present. 
The branchiae, again, wholly differ in structure, while corresponding in number and 
position with the foregoing genus. They are simple processes similar to those in the 
Ampharetidse, tapering from base to apex, the anterior pair being the larger ; moreover, 
all are barred transversely, a feature which distinguishes them from the family just 
mentioned, while they resemble the stems of the branchiae in the ordinary form. In one 
instance an anterior branchia is evidently in process of reparation, as the base is thick, 
and the tip abruptly filiform. The posterior pair are furnished with a short filiform 
tip. The blood of this species is thus satisfactorily aerated at the great depth of 2225 
fathoms, without the aid of the minute appendages generally present in the branchise. 
Dorsally no elevated process is found on the third segment at the base of the posterior 
branchiae as in Pista cristata ; and the anterior border of the fourth segment forms a 
transverse ridge behind them. 
The bristles agree in number with those in Pista, being seventeen pairs, the first 
occurring on the fourth segment. They differ from those of Pista in the great length 
1 Eeport U.S. Commissioner of Fish and Fisheries (1881), 1884, p. 733, jsl. vi. figs. 75-78. 
