1917] Nomland : Fauna of the Santa Margarita Beds 



313 



two heavy ribs, the upper being more prominent, the interspaces 

 between these about the same width as the ribs ; the rib next to the 

 suture above of about same prominence as two near base ; between 

 the ribs at base and the one at top are two spiral lines with narrow 

 interspaces. Incremental lines nearly invisible. Aperture quad- 

 rangular to subcircular. Dimensions : Maximum diameter, about 14 

 mm. ; height unknown. 



Occurrence. — At localities 1697, 1706, north of town of Santa 

 Margarita, type section of the formation, San Luis Obispo County. 

 This species occurs at the type locality with Turritella freya, n. sp. 



