Generic characters of Anguinaria: « The origin convoluted in a spire; the spire almost regular, but becoming cylindrical and twisted, divided laterally by a longitudinal slit; the slit serrated. Aperture orbicular, open. » (C. F. Schumacher: Essai d’un nouveau système des habitations des vers testacés, Copenhagen 1817, p.262. Specific characters: « The surface slightly streaked. »

S. obtusa: « Shell elongated, whorls large, spirally rather finely lirated, smoother on the umbilical face, thickened on the outside and transversely fissured ; spiral slit simple, frequently closed towards the apex. Mediterranean Sea. It is S. anguina of Phil., Sowb., etc., but not of Linnaeus. There are Vars. rosea, Montr., and costae, Cantraine. »

Unlike some indo-pacific members of the genus, the slit is always smooth. This is the reason why Mörch places this species in the section B of his work: « Rima simplex; apex plerumque haliotoideus; primus fissuram nulla habet. » (O. A. L. Mörch: “Review of the genus Tenagodus Guettard”, Proceedings of the Zoological Society of London vol. 28, London 1860 (1861), p.407).
 
« Protoconch: formed by two whorls (height 300µm, width 210µm), yellow-beige, planktotrophic; last whorl sculptured near the suture by small pustules; about four spiral ridges on the lateral-basal side, created by a regular sequence of pustules. » – S. Schiaparelli: “Taxonomy of the family Siliquariidae (Mollusca, Caenogastropoda) in Eastern Atlantic Ocean and Mediterranean Sea”, Italian Journal of Zoology vol. 69, 2002, p.247.