se) SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 134 
material may be almost entirely lacking. This is the case in the first 
whorl of nearly all specimens, the chambers of which have often been 
excavated. Color light brown to fawn with dark brown early cham- 
bers. Chambers: Test of three to three and a half whorls with five or 
six chambers in the last whorl. Chambers increasing regularly in 
size; slightly inflated dorsally, more so ventrally. The last chamber 
possesses a narrow, siphonlike lobe which may partially obscure the 
umbilicus. From this ventral lobe of the last chamber, a “plate” of 
sand grains may extend over the whole umbilicus. Sutures: De- 
pressed ; straight dorsally and straight or slightly sinuous ventrally. 
Aperture: Typically situated at the umbilical end of the ventral lobe 
of the last chamber and directed forward. In some specimens it is 
possible to look into the last aperture and see the penultimate aperture 
opening into the back of the siphonlike lobe of the last chamber. Ifa 
plate extends across the umbilicus, there may be irregularly shaped 
secondary apertures present on one or both sides of it. Size: Maximum 
diameter of holotype 0.43 mm. Maximum thickness of holotype 
0.20 mm. 
Locality—Holotype (U.S.N.M. No. P5107) and figured paratype 
(U.S.N.M. No. P5108) from sample J.S. 273, Carenage Swamp, west 
coast of Trinidad. 
Distribution.—This species is fairly common in some of the Trini- 
dad swamps as, for example, in the Carenage Swamp where it is 
found in considerable numbers associated with Haplophragmoides 
manilaensis Andersen (see p. 3 for note on conditions in this area). 
In the rivers its distribution is sporadic. 
Remarks.—Siphotrochammina lobata Saunders differs from Tro- 
chammina laevigata Cushman and Bronnimann in the nature of its 
aperture. Siphotrochammina lobata has a circular aperture at the 
umbilical end of a ventral lobe of the last chamber whereas Trocham- 
mina laevigata has an interiomarginal slit surmounted by a lip and 
situated on the ventral side of the last chamber. In Siphotrochammina 
lobata the umbilicus, and the primary aperture as well, may be ob- 
scured by a “plate” of sand grains, but such a phenomenon has not 
been observed in Trinidad material of Trochammina laevigata. ‘The 
two species are found associated in the same localities. 
Siphotrochammina lobata differs from Tiphotrocha comprimata 
(Cushman and Bronnimann) emend. Saunders in that the apertures 
do not open separately into the umbilicus. In both species, the um- 
bilicus may be covered by a platelike outgrowth from the chambers. 
