REPORT ON THE ANNELIDA. 
453 
Pista fasciata, according to Marenzeller/ shows a smoothly rounded margin, whereas 
the example procured by the Challenger has a process similar to that shown in the hook 
of the same author’s Pista maculata. Unfortunately, Grube in many cases did not 
figure the hooks of his species, and even when they were represented the artist failed to 
appreciate their exact characters. 
Pista ahyssicola, n. sp. (PI. XXVIIa. fig. 33 ; PI. XXXVIIIa. fig. 1). 
Habitat. — Trawled at Station 157 (midway between the Antarctic region and 
Australia), March 3, 1874 ; lat. 53° 55' S., long. 108° 31' E. ; depth, 1950 fathoms ; 
bottom temperature 32°T, surface temperature 37°‘2 ; sea-bottom. Diatom ooze. 
An injured fragment of the anterior region of a somewhat large species, measuring 
48 mm. in length, and having a diameter of 4 mm. at its widest part in front. 
So far as can be noticed from the example, the general structure of the exterior of 
the body agrees with that in Pista cristata. Only a single branchial process is attached, 
and this presents a longer, but also transversely barred pedicle, and a more elongated 
and more lax series of whorls than in the form just mentioned. Comparatively little 
reliance can, however, be placed on the appearances of these variable parts. 
A comparison of the bristles with those of Pista cristata from Shetland shows that 
though the species procured by the Challenger is considerably larger, the bristles are 
more slender and their tips more tapered, while the winged region at the extremity of 
each is somewhat longer. It is a feature of interest in these tufts that the developing 
bristles, the tips of which just project beyond the setigerous region, show the distinctive 
characters in a marked manner. The extremities of the bristles of this form are not so 
attenuate as in Eupista darioini. 
In comparing the hooks (PL XXVIIa. fig. 33) with those of Pista cristata it is found 
that both are boldly striated from the crown above the great fang downward, the striae, 
perhaps, being most pronounced in the abyssal form. In the latter the posterior (dorsal) 
line, further, presents a much bolder projection interiorly, a feature very evident on 
contrasting the anterior and posterior outlines in each case. The gulf beneath the great 
fang in the new form is smaller than in Pista cristata, and the distance from the inner 
end to the mucro or intermediate spine is much shorter. The lower part of the uncinus, 
again, is more massive. It is not always easy to make out the precise outline of the 
hook interiorly, since the thinner layer to which the long posterior process is attached 
seems to alter under pressure, and therefore is variable in its relation in regard to the 
harder base of the hook, which is indicated by the inner line in the figure. 
The intestine contains a somewhat firm whitish mass, consisting of numerous Diatoms, 
1 Siidjapan. Armel., op. cit, p. 202, Tab. i. fig. 4. 
