Shell resembling Tylotiella, but protoconch narrowly conical, of 3,5-4 whorls; spiral microstriae faint or absent. Radula drilliine, resembling that of Clavus, but marginal plate shaped like a carving-knife, with its blade prominent and 'heeled', occupying nearly two-thirds of length of tooth. In shell characters, Iredalea is not readily separable from Crassopleura Monterosato, 1884, from the Mediterranean. The radula of a specimen of C. maravignae from the Mediterranean coast of France, kindly made available by Dr P. Arnaud. is certainly drilliine, but differs from that of Iredalea exilis (Pease, 1868) in its peculiarly bent marginal plates , the blades of which resemble those of Clavus in extent. The significance of this difference must remain uncertain until more data on members of the complex are available, but for the present Iredalea is recognised as a valid genus.

Kilburn (1988) remarked the close resemblance in shell characters of members of Iredalea Oliver, 1915 and the monotypic Crassopleura Monterosato, 1884, based on Pleurotoma maravignae Bivona Ant. in Bivona And., 1838 from the eastern Atlantic to the Mediterranean Sea, but suggested that the two genera can be distinguished on the basis of radular features. More recently Scarponi & Delia Bella (2004), while discussing Crassopleura maravignae, noted that two forms of this species can be recognized on the basis of the number of axial ribs, namely a Pliocene form bearing 14-18 axial ribs on the last whorl and a Pleistocene one with more numerous ribs (21-25). The authors also remarked that the parietal pad of C maravignae tends to form a moderately deep, narrow and posteriorly directed spout with the end of the outer lip. According to Scarponi & Delia Bella (2004) this feature, not observed in members of Iredalea, supports recognition of Crassopleura and Iredalea as distinct genera. However, in the Pliocene specimen of C maravignae (Scarponi & Delia Bella, 2004: plate 1, fig. 2), the posterior spout is rather weak or even absent as in the recent specimens figured in the WoRMS register (Appeltans et al.9 2012) (accessed at http://www.marinespecies.org/aphia.php?p:=taxdetails&id=:139659).