242 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Range. Atka Island, Aleutians, to San Diego, Cortez Banks, Chile. 
This is the shell we have called Puncturella cucullata Gould. It differs 
from that species in having more ribs, thirty-four main ones and with fine 
ones in the interstices; while Puncturella cucullata has eighteen main ribs, 
with an uneven number in the interstices. (Oldroyd.) 
Puncturella major Dali, 1891 
Proceedings of the United States National Museum, 14:189; 17:712; PI. 26, fig. 4. 
Shell resembling galeata in general and especially in the interior, but 
very much larger; radii alternately large and small from the beginning; 
shell white; anterior slope rectilinear, posterior slope slightly arched and 
a little longer; internal margin crenulate. Length, 57; breadth, 42; height, 
27 mm. (Dali.) 
Type in United States National Museum. Type locality, U.S. Steamer 
“Albatross” Station 3262, off coast of Akutan Island, Bering Sea, in 43 
fathoms. 
Range. Pribilof Islands, Bering Sea, to Dixon Entrance, Alaska. 
Puncturella longifissa Dali, 1914 
Nautilus, 28:63. 
Shell is low, narrow, small, with an arcuate back, strong radial threads, 
very posterior apex, and the slit half as long as the distance from the apex 
to the anterior margin. (Dali.) 
Type in United States National Museum. Type locality, Bering Island, 
Bering Sea. 
Range. Known only from type locality. 
Puncturella carophylla Dali, 1914 
Nautilus, 28:63. 
Shell minute, high, cylindro-conic, with strong, even, radial threads, 
resembles nothing so much as a miniature solitary coral. (Dali.) 
Type in United States National Museum. Type locality, off San Diego, 
California, in 40-80 fathoms. 
Range. Known only from type locality. 
Genus MEGATHURA Nuttall (in Pilsbry), 1891 
Shell large, oblong-oval, embedded in the mantle, but large enough to 
cover most of the upper surface of the animal; apex a little in front of 
the middle, entirely removed by the large oval perforation; edges of shell 
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