The Hydroids and the MedusaePodocoryne Areolata, P. Borealisand P.Carnea

Abstract

Three species of medusae of the genusPodocoryneM. Sars have been collected in the Clyde Sea Area:P. hartlaubiNeppi & Stiasny,P. borealis(Mayer) andP. cameaM. Sars. Their hydroids have also been found there, and medusae liberated in the laboratory have been reared to maturity. Detailed illustrated accounts of the hydroids and of the developmental stages of the medusae are given.The hydroid ofP. hartlaubiproves to be identical with the hydroidPodocoryne areolata(Alder), a species long known to liberate medusae, which however have not previously been referred with certainty to any known species of medusa. By priority the nameP. areolatahas seniority overP. hartlaubiand applies to both hydroid and medusa. The hydroidP. hartlaubireported from Naples by Yamada is discussed, and is considered to be identical withP. areolata. In the Clyde Sea Area the hydroid has been found only on certain small gastropod shells occupied by hermit-crabs.The hydroid ofP. borealishas hitherto been very inadequately known. The hydroid is very common in the Clyde Sea Area, living on a variety of host animals on muddy grounds. Colonies have also been reared in the laboratory from ripe medusae caught in the sea. Abundant material has accordingly been obtained, making possible a full description of the species.