20 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
A. tenuis, n. 
Plate I. Figs. 6-8. 
More or less slender cylindrical or fusiformed tubes, usually tapering to the 
ends, with constricted apertures. Tube-channel smooth, with faint traces of 
spurious septa. Wall loosely cemented of coarse sand, light grayish, compara- 
tively thick. Length 5-10 mm.; diam. 1-1.5 mm. 
Fig. 6, a broken specimen; Fig. 7, transverse section of the same; Fig. 8, the 
tube laid open, showing spurious septation. 
Pacific. 995 fathoms; scarce. 
A. vermiformis, n. 
Plate I. Fig. 9. 
Tube more or less tortuously bent, usually constructed of dark grayish mud ; 
the apertures somewhat constricted at the more or less tapering ends. Length 
about 10-13 mm. The surface of dried specimens is often provided with an- 
nular fine crevices. 
Caribbean Sea. A few specimens from 940 fathoms. 
RHIZAMMINA Brapy. 
R. indivisa Brapy. 
R. indivisa Brady, 1884, Challeng. Rep., [X. p. 277, Plate XXIX. Figs. 5-7. 
Stout tubes of this form have been met with. They differ from Astrorhiza 
vermiformis only in having the test constructed principally of Foraminifera tests 
instead of mud. The reason why Brady has assigned this form to Rhizammina 
is not quite clear. 
Pacific. 1201 fathoms; scarce. 
Gulf of Mexico. 1345-211 fathoms; scarce. 
R. algeeformis Brapy. 
Rhizammina algeformis Br. (1879), 1884, Challeng. Rep., IX. p. 274, Pl. XXVIII. 
Figs. 1-11. 
A single but monstrous tuft of this singular Foraminifer has been met with 
in the Pacific. The height of the tubes exceeds sometimes 38 mm. 
Pacific. 1879 fathoms. 
