« Shell elongate, usually moderately compressed, may be rostrate; shell gape, if present, restricted to short posterior margin where siphons protrude; concentric sculpture usually present which may be strongly incised; middle and inner shell layers non-nacrous; teeth chevron-shaped; ligament internal or external with resilium. » – Allen, Sanders & Hannah: “Studies on the deep-sea Protobranchia (Bivalvia); the subfamily Yoldiellinae”, Bulletin of the Natural History Museum (Zoology) vol.LXI-1, London 1995, p.12.
 

« This group includes a large number of small species, both living and fossil, in which the shell is rather short, usually ovate or swollen, with a small, acute, or subacute, unicarinate rostrum, situated medially or submedially, and defined below by an emargination or undulation in the postero-ventral margin. The postero-dorsal margin is usually convex. The escutcheon or ligamental area is distinctly defined by the carina, but is not sunken. The chondrophore is usually small but distinct. » – Verrill & Bush: “Revision of the genera of Ledidae and Nuculidae of the Atlantic coast of the United States”, American Journal of Science ser.4 vol.III, New Haven 1897, p.54.
 

« Shell elongated, acuminate in front, often truncated or emarginate; ligament internal; hinge with small posterior teeth, gradually increasing; the anterior very large, also increasing by gradation. » – A. Risso: Histoire naturelle des principales productions de l’Europe Méridionale vol.IV, Paris 1826, p.319-320.
 

« The distinctive characters of Saccella can be summarised as follows: an anterior keel or fold, a shallow rostral sulcus, a well-defined rostral keel, a pointed, not particularly long rostrum and an internal posterior tubercle. The anterior keel is variable in strength, from well-defined and step-like to feeble, as a shallow flexure. The rostral sulcus can be anteriorly bounded by a weak ridge. The rostral keel is sharp, straight or more commonly curved, delimiting a rather wide, mostly convex and poorly sculptured postero-dorsal area. The rostral tubercle is a shallow, slightly elongate, ridge-like rise, close to the ventral margin. […] The rostral tubercle of Saccella seems to have a relic nature, since it cannot act as a wall to bound the inhalant siphon because of its small size. Saccella typically has a sculpture of commarginal ribs, more or less coarse, extensive and closely set, becoming somewhat lamellar posteriorly. There is a tendency to the loss or strong attenuation of sculpture, as seen by the present writer in some Miocene species from the Mediterranean, and by Maxwell (1988) and Beu (2006) in fossil and Recent species from New Zealand. Furthermore, Beu (2006) reported the occurrence of a periostracal microsculpture of pustules and short spines.The ligament is internal, within a rather wide triangular resilifer, with a small external amphidetic component, relic of the early, mainly external ligament occurring in most nuculanids (Ockelmann & Warén, 1998).The prodissoconch has a net-like sculpture,similar to that of Nuculana (Ockelmann & Warén, 1998,fig. 5g). » – R. La Perna: “ Revision of the Nuculanidae (Bivalvia: Protobranchia) from the Cerulli Irelli collection (Mediterranean, Pleistocene)”, Bollettino della Società Paleontologica Italiana vol.46(2-33), Modena 2007, p.126.