CLASS GASTROPODA 
91 
Borsonella dalli Arnold, 1903 
Plate 6, fig. 8 
Paleontology of California, 201; PI. 6, fig. 2. 
Shell small, fusiform; spire elevated; apex mammilliform; whorls 
eight, sharply angulated a little anterior of middle; body-whorl less angu- 
lated than those of the spire; 'posterior portion flat to slightly concave, 
anterior portion slightly convex; first four whorls slightly nodose on 
angle; ornamentation consists of fine oblique incremental lines which are 
convexly angulated posteriorly just posterior to angle of whorl; suture 
deeply impressed, distinct; aperture elongate-elliptical; outer lip thin, 
arcuate anteriorly; inner lip incrusted; columella slightly recurved, with 
one prominent plication in middle of aperture; posterior sinus prominent; 
anterior sinus rather short. Long, 23.5; lat., 9; body whorl, 13; aperture 
including canal, 10 mm. (Arnold.) 
Type in United States National Museum. Type locality, Lower San 
Pedro series, at Deadman Island. 
Range. Drake’s Bay, California, to Coronado Islands; also Pleistocene 
of San Pedro. 
This was described as Pleurotoma ( Borsonia ) dalli by Arnold. 
Borsonella coronadoi Dali, 1908 
Bulletin, Museum of Comparative Zoology, 43 :277; PI. 14, fig. 2. 
Shell slender, acute, pinkish white, with a pale brown periostracum 
and about ten whorls; spire longer than the aperture, the nuclear whorls 
smooth, turgid, the subsequent turns carrying a rounded low keel, usually 
in front of the middle of the whorls forming the spire, the area between 
which and the suture is flatly impressed, the whorl in front gently rounded; 
on some of the early whorls the keel is slightly undulated, but not regu¬ 
larly nodulous; besides the lines of growth, both fasciole and the anterior 
part of the whorl show indications under a lens of obscure regular distant 
spiral striae, and are also more or less marked with a faint vermicular 
reticulation of the surface; suture not appressed, distinct; aperture nar¬ 
row, anal sulcus deep and wide, reaching the suture; outer lip thin, sharp, 
arcuately produced; inner lip slightly eroded, polished, with no callus; 
plication at the proximal end of the pillar; axis impervious, canal short, 
wide, deep, slightly recurved with a fairly well-marked fasciole. Long, of 
shell, 29; of last whorl, 16.5; of aperture, 12; max. diam., 9 mm. (Dali.) 
Type in United States National Museum, No. 110608. Type locality, 
Station 2931, off Los Coronados Islands. 
Range. San Clemente Island to Coronado Islands. 
This was described as Bor sonia (Borsonella ) coronadoi by Dali. 
