32 AUSTRALASIAN ANTARCTIC EXPEDITION. 
The single specimen is small, translucent white, broadly ovate to lozenge-shaped 
in shape with a broad obtusely angled hinge line. The sides are rounded, passing 
without a marked angle into the slightly truncate but gently rounded front. The 
convexity is moderate, the ventral valve taking the larger share. There is a faint 
anterior median sinus in the dorsal valve producing a ventrally directed sinuation in 
the anterior commissure. The beak is blunt, short, sub-erect without marked beak 
ridges, truncated by a submesothyrid foramen which opens into a delthyrium only 
partially closed by lateral deltidial plates. The surface of the shell is smooth, with 
feebly developed growth lines, not crowded anteriorly, indicating a youthful shell. 
The pores are moderately large, but not so large as in M. joubini, the pore density 
being low, only 70 per sp. mm. 
The loop is in a late Terebratelliform stage and extends forward to three-quarters 
the length of the dorsal valve; the ascending branches are broader than the descending, 
and occupy only one-third the breadth of the valve. The septum and cardinalia are 
of the Magellaniform pattern with narrow and short hinge plates. 
As the specimen is apparently not fully grown, it is uncertain whether it should 
be referred to Terebratella or Magellania. In shape it lies between Magellania joubini 
and M. fragilis Smith, and is broader than specimens of the former of the same length, 
and narrower than growth lines of the latter at the same length. From M. joubina it 
is further distinguished by the absence of the strong growth lines of that species and 
by the smaller pores. Although the less developed beak characters, as compared with 
M. fragilis, might be considered as due merely to its youth, the more advanced folding 
in so much smaller a shell shows that it cannot be the young of this species. It is 
probably the young of a new species. 
Dimensions—Length 13 mm., breadth 11-5 mm., thickness 6-5 mm. 
MAGELLANIA (2) sp. 
(Plate XV, fig. 23.) 
Habitat.—Station 2, lat. 66° 55’ S., long. 145° 21’ EB. (off Adelie Land), 288-300 
fathoms, 28th December, 1913. Sea-bottom, ooze ; temperature 1-80° C. 
A series of small specimens, from 6 mm. to 12 mm. in length, and all obviously 
young shells, must apparently be referred to a new species. As in the case of the last 
described specimen, the generic position must remain uncertain until adult shells have 
been examined. None of the present series have passed the Magelliform stage, and 
they may be referable to Magella, Terebratella ov M agellania. 
The largest specimen (length 12 mm., breadth 10 mm., thickness 5 mm.) 1s 
regularly ovate with a hinge line moderately broad and obtusely angled. The con- 
vexity is slight, the greater part being taken by the ventral valve. ‘There is no marked 
sinus in the dorsal valve, but a gentle and broad ventral sinuation in the anterior com- 
missure. The beak is short, sub-erect, with moderate beak ridges and a relatively 
