Halistemma elegans – synonym of Nanomia cara
Halitholus cirratus – synonym of Halitholus yoldiaarcticae
Haplostylus normani – synonym of Gastrosaccus normani
Helgicirrha schulzii – synonym of Helgicirrha schulzei
Helix Janthina – synonym of Janthina janthina
Hemimysis pontica – synonym of Hemimysis lamornae
Here, it does raise the question as to whether by the rule of priority D. rostrata (Goodsir, 1843) shouldn't be th – synonym of Diastylis laevis
Heterofusus retroversus – synonym of Limacina retroversa
Heterofusus retroversus – synonym of Limacina retroversa retroversa
Heterosquilla eusebia – synonym of Platysquilla eusebia
Hippocrene aurea – synonym of Bougainvillia principis
Hippocrene pyramidata – synonym of Bougainvillia pyramidata
Hippocrene superciliaris – synonym of Bougainvillia superciliaris
Hippopodius luteus – synonym of Hippopodius hippopus
Hippopopus neapolitanus – synonym of Hippopodius hippopus
Holothurium zonarium – synonym of Soestia zonaria
Homarus vulgaris – synonym of Homarus gammarus
Hyalaea cuspidata – synonym of Clio cuspidata
Hyperia sueri – synonym of Hyperia medusarum
Hyperoche kroeyeri – synonym of Hyperoche medusarum
Hyppolite gaimardii – synonym of Eualus gaimardii
Hyppolite gordoni – synonym of Caridion gordoni
Hyppolyte cranchi – synonym of Thoralus cranchii