76 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Also a pelagic species, that nearly always accompanies the preceding in both 
oceans. Although the form represented by d’Orbigny in his memoir on the 
Chalk Foraminifera from Paris does not quite agree with our recent form, its 
margin not tending to an angulous circumference, as in the latter form; but 
that feature is of too small importance to establish a specific denomination for 
our form. 
On both sides of Isthmus. Pelagic. 
ALLIED FoRM: — 
P. crassa D’Ors. 
Rotalina crassa D’ORB., 1840, For. Craie bl. Paris, Mém. Soc. Géol. France, IV. 
p. 32, Pl. IIL. Figs. 7, 8. 
P. crassa Br., 1884, Chall. Rep., IX. p. 694, Pl. CLI. Figs. 11, 12. 
Although Brady’s designation of d’Orbigny’s form from the Chalk of 
Paris does not exactly agree with this, it is not necessary to adopt a new 
name for the recent variety, the discrepancies being too trifling between 
the two forms. The recent one has usually the last circumvolution divided 
into four segments, while d’Orbigny’s form has six; the aperture is also 
wider in the latter. 
Caribbean Sea. A single specimen only found; probably pelagic. 
P. elegans v’Ors. 
Rotalia (Turbinulina) elegans D’ORB., Tab. Méth., An. Se. Nat., VII. p. 276, No. 54. 
Rotalina Partschiana v’OrB., 1846, Bass. tert. Vienne, p. 153, Pl. VII. Figs. 28-30, 
Pl. VIII. Figs. 1-3. 
P. elegans Gots, 1882, Ret. Rhizop. Caribb. Sea, Sv. Vet. Ak. Hdl., XIX. 4, p. 111, 
Pl. VIII. Figs. 2838-285. 
P. elegans, partschiana Br., 1884, Chall. Rep., IX. p. 699, Pl. CV. Figs. 3-6. 
P. elegans Goiis, 1894, Arct. & Scand. Foramf., Sv. Vet. Ak. Hdl., XXV. 9, p. 97, 
Pl. XVI. Fig. 808. 
Reaches a high development in deep water, particularly in the Pacific. The 
large specimens have the sutures less limbated, the edge sharper, and the spiral 
side more flat, than the smaller ones. The aperture is usually a narrow slit on 
the marginal top of the last segment, but sometimes it has the regular situation 
in common with its congeners, being very narrow. Sometimes such an aper- 
ture continues in an apical slit. 
Pacific. 695-1832 fathoms; not scarce. 
Caribbean Sea. 300-1830 fathoms; smaller, and not so common. 
P. Schreibersii p’Ors. 
Rotalina Schreibersii D’ORB., 1846, Bass. tert. Vienne, p. 154, Pl. VIII. Figs. 4-6. 
P. elegans var. trochus Goés, 1882, Ret. Rhizop. Caribb. Sea, Sv. Vet. Ak. Hdl., XIX. 
4, p. 112, Pl. VIII. Figs. 286-288. 
P. schreibersii Br., 1884, Chall. Rep., IX. p. 697, Pl. CXV. Fig. 1. 
