130 
“TERRA NOVA” EXPEDITION. 
the tree part of the tergum is shorter ; the lower border of the same plate is concave : 
the lateral border of the scutum is much less convex; the inframedian plate is 
pentagonal, with a thickened triangular area which leaves at the side structures like 
the radii of a Balcinus ; the umbo of the rostro-lateral projects beyond the outline of 
tlie capitulum : the scales of the peduncle are narrower. 
One specimen was taken at Station 349 (off Butter Point, western shore of 
McMurdo Sound. 80 fathoms), growing on a pyenogonid of the genus Nynvphon. 
i’lG. 3. — Scalpellum (Arco- 
scalpellum) compaetum, 
n. sp. (?). X 9. i.m., 
inframedian plate of 
opposite side. 
Fig. 4. — Lithotrya 
atlantica, n. sp. 
Capitulum. x 6. 
Fig. 5.—Jaws of Lithotrya. a, mandible of L. atlantica 
a, mandible of L.pacifica ; b, maxilla of L. atlantica 
//, maxilla of L. pacifica. 
4. S. (H.) compaetum, n. sp. (?). Fig. 3. 
An Arcoscalpellum of about the same size as the supposed young stage of >8. 
discovery i (length of capitulum 5 • 5 mm.), but differing from it as follows: the lateral 
border of the scutum is not notched ; the produced angle of the upper lateral plate is 
much sharper ; the cariuodateral is not notched where it meets the shoulder of the 
oarina: the umbo of the rostro-lateral projects beyond the outline of the capitulum, 
but transversely, not with an upward trend, as in S. ni/mplionis; the inframedian plate 
is triangular with the apex distal (except on one side of one specimen, where it is very 
narrow, with a spear-head at the distal end) ; the plates of the peduncle are narrower 
and more widely separated. 
One specimen was taken at Station 356 (off (Iranite Harbour, western entrance to 
McMurdo Sound, 50 fathoms). 
I 
