404 
THE VOYAGE OF H.M.S. CHALLENGEK. 
The dorsal, also bulky, cover on the other hand a much more extensive area than those 
in the previous species. The oblique muscles are inserted exactly over the outer border 
of the nerve-area. A minutely granular mass occurs on each side at the hiatus between 
the longitudinal muscles. It probably represents the reproductive elements. 
Praxilla (?) challengerice, n. sp. (PI. XXXVa. fig. 5). 
Habitat . — Dredged at Station II. (off Setubal on the coast of Portugal), January 13, 
1873 ; lat. 38° 10' N., long. 9° 14' W.; depth, 470 fathoms ; surface temperature, 57°'0 ; 
sea-bottom, green mud. 
A fragment of the posterior region of a slender elongated form which has apparently 
been dried. 
The chief peculiarity about the configuration of the body is the condition of the tail, 
which is pointed, but whether this be the result of injury or otherwise is unknown. The 
acutely tapered organ presents a notch for the anus, probably on the dorsal surface. 
The last segment of the body (i.e., the ring behind the terminal row of hooks) is much 
elongated, slender, and thrown into several dilatations like the body of a Sipunculus. 
The other segments are also proportionally long. 
The hooks (PL XXXVa. fig, 5) have a comparatively short distal region, and a 
characteristic and pronounced shoulder. The teeth above the great fang point forward, 
and thus make a long crown. Four of these are especially distinct, and a fifth less 
evident. A slight interval occurs between the great fang and the origin of the fibres. 
The bristles have winged, tapering tips. 
The hooks are certainly peculiar in the shortness of the upper region, and approach 
those of certain species from Guernsey and Herm, though the distal region in the latter 
is longer. 
Praxilla capensis, n, sp. (PI, XXXVa. fig. 8). 
Habitat . — Dredged at Station 141 (Cape of Good Hope), December 17, 1873; lat. 
34° 41' S., long, 18° 36' E.; depth, 98 fathoms; bottom temperature 49°’5, surface 
temperature 66°’5 ; sea-bottom, green sand. 
Only two fragmentary examples of the anterior region were found, the largest 
measuring about 30 mm., with a diameter of fully 2 mm. 
This form approaches the succeeding from Kerguelen, and also Praxilla prcBtermissa, 
in general appearance. The central cephalic ridge, however, does not extend so far 
backward (or dorsally), and the two lateral ridges overhanging the grooves do not proceed 
even so far, the three segments following the buccal (which are also longer proportionally 
