- Collodes armatus
- Collodes inermis
- Collodes rostratus
- Collodes trispinosus
- Collosphaera huxleyi
- Collosphaera macropora
- Collosphaera tuberosa
- Colobonema sericeum
- Comantenna curtisetosa
- Conacon foliaceus
- Conaea expressa
- Conaea rapax
- Conchellium capsula
- Conchidium caudatum
- Conchidium terebratula
- Conchophacus diatomeum
- Conchopsis compressa
- Conchopsis orbicularis
- Condylostoma patens
- Copilia hendorffi
- Copilia lata
- Copilia mediterranea
- Copilia mirabilis
- Copilia quadrata
- Copilia vitrea
- Cordagalma cordiforme
- Cornucalanus chelifer
- Cornucalanus robustus
- Cornucella maya
- Cornutella profunda
- Corocalyptra cervus
- Corocalyptra columba
- Corocalyptra kruegeri
- Corolla calceola
- Corolla cupula
- Corolla intermedia
- Corolla ovata
- Corolla spectabilis
- Corycaeus affinis
- Corycaeus agilis
- Corycaeus amazonicus
- Corycaeus clausi
- Corycaeus crassiusculus
- Corycaeus flaccus
- Corycaeus furcifer
- Corycaeus giesbrechti
- Corycaeus latus
- Corycaeus lautus
- Corycaeus limbatus
- Corycaeus longistylis