| Synonym | Author | CoL Status | Valid | Synonymy | Combination |
|---|---|---|---|---|---|
| Caecum amblyoceras | (Woodring, 1959) | synonym | No | junior synonym |
new combination |
| Caecum apanium | (Woodring, 1928) | synonym | No | junior synonym |
new combination |
| Caecum bitumidum | Folin, 1869 | synonym | No | junior synonym |
original combination |
| Caecum cingulatum | Dall, 1892 | synonym | No | junior synonym |
original combination |
| Caecum constrictum | Gabb, 1873 | synonym | No | junior synonym |
original combination |
| Caecum contractum | Folin, 1874 | synonym | No | junior synonym |
original combination |
| Caecum coxi | Folin, 1869 | synonym | No | junior synonym |
original combination |
| Caecum crossei | Folin, 1869 | synonym | No | junior synonym |
original combination |
| Caecum deshayesi | Folin, 1869 | synonym | No | junior synonym |
original combination |
| Caecum fischeri | Folin, 1870 | synonym | No | junior synonym |
original combination |
| Caecum imiklis | Folin, 1870 | synonym | No | junior synonym |
original combination |
| Caecum lermondi | Dall, 1924 | synonym | No | junior synonym |
original combination |
| Caecum marmoratum | Folin, 1869 | synonym | No | junior synonym |
original combination |
| Caecum moreleti | Folin, 1869 | synonym | No | junior synonym |
original combination |
| ! Caecum nitidium | unspecified | ambiguous synonym | No | unknown |
|
| Caecum nitidum | Stimpson, 1851 | synonym | No | senior synonym |
original combination |
| Caecum rotundum | Folin, 1869 | synonym | No | junior synonym |
original combination |
| Caecum subinflexum | Folin, 1869 | synonym | No | junior synonym |
original combination |
| Caecum tumidissimum | Folin, 1869 | synonym | No | junior synonym |
original combination |
| Caecum undulosum | Folin, 1869 | synonym | No | junior synonym |
original combination |
| Coecum nitidum | Stimpson, 1851 | synonym | No | senior synonym |
original combination |
| Elephantanella lermondi | (Dall, 1924) | synonym | No | junior synonym |
new combination |
| Elephantanella nitidum | (Stimpson, 1851) | synonym | No | senior synonym |
new combination |
| Meioceras nitidum | (Stimpson, 1851) | accepted name | Yes | senior synonym |
new combination |
| Meioceras tumidissimum | Folin, 1869 | synonym | No | senior synonym |
original combination |
| Micranellum lermondi | (Dall, 1924) | synonym | No | junior synonym |
new combination |
| Micranellum nitidum | (Stimpson, 1851) | synonym | No | senior synonym |
new combination |