250 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Subgenus Impasrs Smith, 1873. 
Shell larger with whorls flat and rapidly enlarging ; sculpture of young and 
old diserepant. Young, faintly axially ribbed, the suture appressed, with no 
sulcus or band; the adult smooth, a thin wash of callus on the body, extending 
over the whorl behind the line of the following suture; inner lip not raised, the 
aperture with no posterior channel or anterior canal, but a deep siphonal suleus, 
the pillar with one more or less hidden keel. "Type Terebra coerulescens Lamarck. 
The band of enamel behind the suture is not very conspicuous and may not be 
of much systematic value; the other characters, however, seem to give it a 
certain value. 
DUPLICARIA DALL. 
Dupuicarıa Dall, Nautilus, March, 1908, p. 124. 
Shell small, acute, similarly sculptured throughout, with sharp, regular, 
numerous axial ribs crossing the flat whorls and divided by a conspicuous spiral 
sulcus; suture distinctly channelled; pillar with a single keel, the columellar 
lip not callous or raised, the canal obsolete, the aperture with no posterior 
channel, Type Terebra duplicata Lamarck. 
This is Myurella Troschel, not Hinds. The anatomical characters have already 
been mentioned and forbid its consolidation with the other genera. It is the 
only group in the family with a channelled suture, 
SPINEOTEREBRA SACCO. 
Subgenus SPINEOTEREBRA Sacco, 1801, s. s. 
Shell rather elongate, with knobby axial sculpture, no spiral sculpture, an 
impervious axis, and a markedly callous pillar lip. Type Zereöra spinulosa 
Doderlein, Tortonian. The siphonal fasciole is nearly obsolete. 
Subgenus MazaTLANIA Dall, 1900. 
Shell shorter, buccinoid, thin, with sparse knobbed axial ribbing, spiral sculp- 
ture conspicuous toward the canal; the pillar gyrate, the axis pervious, the pillar 
lip bare, the siphonal fasciole well developed. Type Terebra aciculata Lamarck. 
Mazatlania is Euryta Adams, 1853, not of Gistel, 1848. It appears to be a 
descendant of Spineoterebra, which is intermediate between Strioterebrum and 
Mazatlania. The soft parts of both are unknown. 
Terebra (Strioterebrum) panamensis Datt, n. sp. 
Plate 5, figure 10, 
Shell small, acute, twelve-whorled, with rather prominent sculpture and a 
generally brownish tint; nucleus eroded in all the specimens ; subsequent whorls 
