38 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
single instance did I find any of them bearing a sucker. On the first arm 
there are only three or four of these, very low down close to the buccal mem- 
brane ; on the second they are slightly more numerous, on the third there are 
seven or eight, which form a triangular patch with the apex directed towards 
the root of the arm; on the fourth right arm there are about a dozen sim- 
ilarly disposed. 
The fourth left arm (Plate 8, Fig. 5) further shows a remarkable form of 
hectocotylization. This is produced chiefly by a development of the lappets 
and web along the ventral margin of the sucker-bearing surface. The web 
becomes rapidly broader from the proximal end, until at a point about one- 
third along the arm its breadth is three times the diameter of thearm : hence it 
becomes gradually narrower, running off into the arm just before the tip. The 
lappets are correspondingly lengthened and form a series of parallel ribs 
strengthening the membrane. Along their margins (Plate 8, Fig. 6) may be 
seen a series of minute papillae like those described on the other arms. On 
the dorsal margin of the sucker-bearing face is a row of lappets, also provided 
with rows of papillae, but I was not able to find any trace of a web uniting 
them. However, as the web is in all cases very delicate, it is quite possible 
that it may exist. At the root of the arm is the triangular group of papillae 
alluded to above. 
The Radula, which has not been hitherto described, is figured on Plate 8, 
Fig. 9. It consists of the usual seven longitudinal series : the centrals are ex- 
tremely simple, an acute point arising from a plain rounded base; the points 
diverge from the middle line, sometimes to the right, sometimes to the left, 
only about one in six being quite symmetrical. The first laterals have a 
strong pointed tip mounted towards the median aspect of a simple base, the 
points being directed somewhat inwards ; the second laterals are stout, curved, 
and pointed ; the third laterals are much larger, comparatively more slender 
and blunter than the second, and are bent to about the quadrant of a circle. 
38. Abraliopsis, sp. ? 
(Plate 2, Fig. 3.) 
Habitat. — Station 2619 Hyd., Gulf of Panama; March 11, 1891 ; lat. 7° 31^ 
N., long. 78° 42" 30” W., surface to 300 fathoms; temperature, surface 68°; one 
specimen; immature. [H. 64.] 
Station, 14, north of the Marquesas Islands; September 7, 1899; lat. 6° 41' 
N., long. 137? W.; 150 fathoms to surface; temperature, surface, 82°; one 
specimen. [H. 143.] 
My friend Dr. Pfeffer, who examined the former of the above-mentioned 
young specimens, considers it to belong to the Abraliopsis group, partly because 
of the length of the tentacles, and partly because at the extremity of the left 
ventral arm (the right being imperfect) is to be seen a slight knob-like swell- 
ing, which might be a stage in the development of the curious pigmented 
