Hyalea orbignii Rang, 1827: a fossil Cavolinia species (Mollusca, Pteropoda)

In my papers on pteropods (Van der Spoel, 1967, 1968a, 1971) I fully misinterpreted Souleyet’s (1852) remarks on Hyalaea orbignii. Souleyet did indicate a resemblance of Hyalaea orbignii with Hyalaea quadridentata but he did not in any sense state that H. orbignii was a recent species. From Souleyet’s description and illustration I incorrectly got the impression that Hyalea quadridentata var. costata Pfeffer, 1879, was identical to Hyalea orbignii (ms. Rang) (Souleyet, 1852), so that I have given priority to the name orbignii (corrected to orbignyi). This is completely incorrect as Hyalea orbignii is a fossil species already published by Rang in 1827; it belongs to the genus Cavolinia in which it shows most affinity to species like C. globulosa (Gray, 1850) and C. gibbosa (d’Orbigny, 1836). The holotype of Hyalea orbignii is preserved in the Museum d’Histoire Naturelle at Paris, where I have consulted it at the Department of Malacology. As a good figure of the holotype has so far never been published, it is shown here in figures 1-3. The figures by Souleyet (1852, pl. III figs. 16-18) are in all probability also based on this specimen, as in the original description (Rang, 1827) only one specimen is mentioned. These figures are rather small, however, and do not give the most characteristic details. The holotype was fixed on a piece of cardboard, after the figures for the plates of Souleyet’s work had been completed, as could be concluded from the hole in the dorsal side surrounded by fragments of glue. The original description by Rang (1827) is generally correct and as such translated below: