404 
THE VOYAGE OF H.M.S. CHALLENGER. 
peduncle on its dorsal edge. It is triangular in shape and is surrounded by a some- 
what circular raised margin. The atrial aperture is large, and has the form of a 
transverse slit. It is placed on the dorsal edge of the body more than half way back. 
The surface is smooth in most places, but there are two projections on the ventral 
side of the peduncle at the anterior end of the body. A broad band of small pointed 
tubercles runs longitudinally along the ventral edge, and two narrow lines run trans- 
versely one behind the branchial aperture and another in front of the atrial. The latter 
terminates ventrally at the most posterior point of the body in a slight toothed ridge. 
The colour is a dull opaque grey. 
The length of the body (antero-posterior) is nearly 1 cm.' The breadth of the body 
(dorso-ventral) is 6 mm. The length of the peduncle is about 7 cm. The thickness of 
the peduncle is 0'5 mm. 
The Test is thin but tough and opaque. 
The Mantle is moderately strong. 
The Branehial Sae has several slight folds upon each side ; each fold is formed of 
three or four internal longitudinal bars. The transverse vessels are narrow ; they are all 
of the same size, and are placed rather far apart. The internal longitudinal bars are 
much stronger and more closely placed. The meshes are vertically elongated. 
Calcareous spicules are present in the internal longitudinal bars, and occasionally 
extend into the transverse vessels ; they are not numerous, but are large and slightly 
branched. 
The Tentaeles are pinnate. They are provided with spicules. 
Loeality. — Station 241, June 23, 1875 ; lat. 35° 41' N., long. 157° 42' E.; depth, 
2300 fathoms; bottom temperature, 35°T F.; bottom, red clay. 
One specimen of this new species of Culeolus was dredged at Station 241, in the 
Pacific Ocean, to the west of Japan, from the great depth of 2300 fathoms. The large 
species Culeolus murrayi was obtained at the same locality. 
Culeolus willemoesi is the smallest species of Culeolus known. It differs from Culeolus 
recumhens and Culeolus perlueidus in having the peduncle running anteriorly from the 
body; it differs from Culeolus perlatus and from Culeolus murrayi in having no marked 
band of tubercles around the atrial aperture ; and lastly, it differs from both Culeolus 
wyville-thomsoni Culeolus moseleyi in the surface of the test, which is neither perfectly 
smooth, as in Culeolus wyville-thomsoni, nor yet evenly roughened all over as in Culeolus 
moseleyi. It also differs from Culeolus murrayi, Culeolus loyville-thomsoni, and Culeolus 
moseleyi in the position of the atrial aperture, and from Culeolus recumhens and 
Culeolus perlueidus in the shape of the body. In some respects it is more like Culeolus 
perlatus than any of the previously described species, but differs from it in the 
peduncle, the branchial aperture, the surface of the test, and other points. 
