Boone, Mollusca, Cruises of "Ara" and "Alva" 301 



The dimensions and variations existent within the present 

 series is as follows, all measurements given in millimeters : 



Horizontal, Horizontal, 



Long Diameter Short Diameter Altitude Remarks 



46 44 26 Interior smoky gray-brown with green- 



ish opalescence; about 20 primary costae. 

 About 10 primary costae. 



Apical erosion .6; 34 primary costae 

 with 3 secondaries between each pair. 



Interior opalescent green, deep, smoky; 

 14 strong primary costae. 



Interior dark smoky blue-gray ; 48 small 

 eroded costae. 



Interior blackish gray, little opales- 

 cence; 12 strong primary costae. 



Margin semistellate, irregular, 10 pri- 

 mary costae, very fine intermediate 

 striae. 



29 24 15 Primary costae 10, interstices fine- 



ribbed, margin irregular and ten-rayed. 

 Interior steel gray-green with silvery 

 cast. 



55 45 40 Injured; greatly eroded, all primary 



costae eroded, secondary striae small. 

 Interior gray-blue, iridescent. 



50 40 35 12 primary costae, about as many half 



so coarse costae, with interstices fine- 

 ribbed. Interior pearly gray-blue, milky, 

 opalescent. 



46 35 30 20 primary costae of medium size, erod- 



ed, with about 20 secondary striae. In- 

 terior shining steel blue-gray. 



40 35 25 12 coarse primaries and 12 large sec- 



ondaries, margin irregular, crenulate. 



42 32 26 10 coarse primary costae, 10 secondaries 



with 6 to 8 fine striae per section ; mar- 

 gin irregular, pointed. Interior opales- 

 cent, milky, silvery steel blue. 



40 30 21 12 primary costae, about 6 coarse sec- 



ondary costae and numerous fine striae. 

 Interior deep gray with radiating cream 

 lines on inner of costae, all opalescent 

 silvery with faint rose tints. 



36 30 25 10 primary costae with about as many 



coarse secondaries extending in part 

 way to center, intermediate striae fine. 

 Interior light steel gray, darker at mar- 

 gin with milky opalescence. 



32 24 18 10 primaries and 10 eroded secondaries. 



Contour very irregularly oval; margin 

 coarsely pointed. 



60 45 30 Exterior badly eroded; interior also 



worn. 



