What is "cyrtocerinidae"

Cyrtocerinidae is a family of ellemerocerids with slightly endogastric (inwardly curved) breviconic shells with ventral siphuncles that have connecting rings thickened as lobes that project straight into the interior.

Cyrtocerinidae was established by Flower,1946, (Flower 1964) for the genus Cyrtocerina Billings 1865, found at various locations across North America. The shells are generally small, laterally compressed, and dorsum more narrowly rounded than the venter.