Following are comments on the species included in the key. Particular attention has been directed towards new taxonomic structures and our observations are noted as additional comments. Synonymies are found in the most recent references.

Grania americana Kennedy, 1966. Type locality: 0.5 km from North Entrance point, west side of North Bimini, Bahamas. Also known from Florida, Bermuda and Carrie Bow Cay, Belize. Intertidal and shallow subtidal to 10 m in sand and sandy-mud. Completely redescribed in Locke & Coates (1999).

Grania atlantica Coates & Erséus, 1985. Type locality: Continental slope off Massachusetts. Known from off the coast of New Jersey, SW of Ireland (NE Atlantic), N of Surinam, Guinea (W Africa) and Luanda, Angola. Subtidal from 744 to 1518 m in silty-sands and oozes. Completely described in Coates & Erséus (1985) with new information in Rota & Erséus (1996). Additional comments on the species: The anterior bilobed brain region consists of a thin extension which connects to an anterior statocyst (Locke 2000), previously referred to as the "head organ" (Rota & Erséus 1996). The statocyst differs from G. americana in that the statocyst vesicle is elongate rather than bulbous, the anterior medial extension of the brain is longer and three to four statoliths are apparent, but their relative positions seem to differ from those of G. americana (see Locke & Coates 1999). A statocyst was only clearly visible in 3 of 21 preserved specimens.

Grania bermudensis Lasserre & Erséus, 1976. Type locality: Castle Island, St. George's, Bermuda. Known only from Bermuda. Shallow subtidal 8 to 15 m in coarse coral sand with ripple marks. Completely redescribed in Locke & Coates (1999).

Grania hylae Locke & Coates, 1999. Type locality: ENE of Paget Island, St. George's, Bermuda. Also known from Fowey Rocks, Florida. Intertidal and subtidal to 17 m in medium to coarse coral sand, and muddy sand. Described in Locke & Coates (1999).

Grania laxartus Locke & Coates, 1999. Type locality: Ferry Point Bridge, St. George's, Bermuda. Also known from Carrie Bow Cay, Belize. Intertidal in poorly sorted coarse biogenic mud and sand. Described in Locke & Coates (1999).

Grania levis Coates & Erséus, 1985. Type locality: George's Bank (SE of Massachusetts). Also known from off the coast of New Jersey. Subtidal 42 to 79 m in medium to coarse sand. Completely described in Coates & Erséus (1985). Additional comments on the species: Statocyst apparently lacking from holotype.

Grania longiducta Erséus & Lasserre, 1976. Type locality: Cape Cod Bay, Massachusetts. Also known from George's Bank (SE of Massachusetts), off the coast of New Jersey, Delaware and Maryland. Subtidal, 42 to 78 m, in medium to coarse sands. Coates & Erséus (1985) have made taxonomic revisions and annotations. Additional comments on the species: Within the anterior region of the bilobed brain a narrow, possibly spiraled extension was visible, however, a statocyst was not seen anterior to this in 13 fixed and mounted specimens.

Grania monospermatheca Erséus & Lasserre, 1976. Type locality: Cape Cod Bay, Massachusetts. Also known from off the coast of New Jersey, Maryland, North Carolina, NE of Oregon Inlet, Beaufort, North Carolina, and Biscayne Bay, Florida. Subtidal, 3 to 48 m in sandy-gravel. Redescribed in Coates & Erséus (1985). Additional comments on the species: The penial apparatus is a terminal bipartite sac, it lacks a bulbous gland and contains a long stylet within a muscular, modified vas deferens. This is called a Type 6 penial apparatus (Coates 1984; Locke & Coates 1999). A statocyst was not seen in the 40 preserved specimens observed.

Grania reducta Coates & Erséus, 1985. Type locality: Off the coast of Maryland. Also known from Delaware, Maryland, and off the coast of New Jersey. Subtidal, 29 to 65 m in medium to coarse sand. Complete description in Coates & Erséus (1985). Additional comments on the species: Statocyst not observed in 2 preserved specimens.

Randidrilus codensis Coates & Erséus, 1985. Type locality: Cape Cod Bay, Massachusetts. Also known from off the coast of New Jersey and Maryland. Subtidal, 6.7 to 33 m in medium to coarse sand. Additional comments on the species: Statocyst not observed in 5 preserved specimens.

Randidrilus quadrithecatus Coates & Erséus, 1985. Type locality: off the coast of New Jersey. Also known from Maryland. Subtidal, 29 to 58 m in medium to course sand. Additional comments on the species: Statocyst not seen in holotype.