Dromiidae de Haan, 1833

A detailed description of three dromiid foregut-ossicles ( Metadromia wilsoni, Dromia personata and Lauridromia intermedia) is given in Brösing et al. 2002. Remarkable deviations from two further dromiid species ( Stenodromia spinirostris and Hypoconcha spinosissima) are as follows:

Stenodromia spinirostris (Miers, 1881) (Fig. 2 A, B)

The paired prepterocardiac ossicle (IIa) lies anterior to the mesocardiac ossicle (I). Both have a form of narrow, transversally elongated strips.

Hypoconcha spinosissima Rathbun, 1933

The prepterocardiac ossicle (IIa) is unpaired.