522 PROCEEDINGS OF THE NATIONAL MUSEUM: vol.xxiv. 
y-Pyrolofusvs (Beck, MS.) Moiicn, Annales 8oc. Mai. de Belgique, IV, 1869, p. 20 
(no (liay;iioyis, sole example eited, Fusua deformis Gray). 
y-Heliotroph Dall, Proc. Cal. Acad. Sci., V, April, 1873, p. 61. (Type, Ncplunea 
harpa Morch. ) 
Subdivisions of this subfamily ma,y be characterized as follows: 
Genus Chrysodomus. Type, O. antiquum (Linnaeus). 
Shell large, short-fusiform, smooth or spirally sculptured, some- 
times with rude axial ribbing or nodosities; outer coat of the shell 
subtranslucent, with a darker tint than the inner layers and with the 
periostracum inconspicuous; last whorl longer than the spire, with a 
wide aperture, the outer lip flaring or subreflected; pillar flexuous, 
smooth; body without callosities or lirte; the canal rather long, wide, 
and flexuous; animal short and broad, the penis large, usually sickle- 
shaped and with a' small elongated terminal papilla; operculum ovate 
with apical nucleus, nearl}^ closing the aperture; ovicapsules massed, 
either in a heap, as in Buccm.imi^ or in a cylindrical erect group. 
The nepionic shell with a rounded, irregular submammillary nucleus 
and rapidly increasing subsequent whorls. The dental formula is 
I'l'l, the teeth usually tridentate, the central rhachidian cusp and 
outer lateral cusps usually larger, the minor cusps often irregular, 
multiple, or obsolete. The habitat of the genus is in cold water of 
the north temperate or Arctic seas. 
Genus Ecphora Conrad, 1843. Type, Fusus quadrlcostaMis Say, 1824. 
Miocene of Marjdand. Shell vertically depressed, few whorled, the 
last much the largest; canal short, very deep and narrow ^ith a funic- 
ular large umbilical pit; sculpture of strong spiral ribs. 
1 have already shown ^ that this curious shell is probably closely 
related to Chrysodomus. 
Genus Tritonofusus Beck. Type, Fusus islandicus (Gronovius). 
Shell usually smaller than Chrysodomus., elongate-fusiform, smooth 
or spirally sculptured, axial sculpture feeble or none; outer layer of 
the shell chalky, white, with a conspicuous, often villous periostra- 
cum; aperture moderate, with the outer lip acute, entire, not reflected 
or flaring; canal narrow, elongate, and more or less flexuous; pillar 
and body smooth; operculum filling the aperture, formed as in Chry- 
sodomus ; ovicapsules solitar3^ lentiform or hemispherical, attached 
by the whole flat side; nepionic shells small, the apical whorl swollen, 
subglobular, the next succeeding somewhat constricted* and the rest 
regularly increasing. Dentition as in Chrysodomus^ the minor cusps 
variable. 
Subgenus Siphonorbis Morch {SiphmieUa Verrill). Type, Fusus 
lac Justs Morch. 
Rhachidian tooth with a single cusp, and laterals with two cusps; 
nepionic shell beginning with a small regular planorboid coil and the 
^Traus Wagner Inst., Ill, 1890, p. 124. 
