Depastrum cyathiforme occurs in shallow water at Plymouth, Port Erin, and in other localities on the coasts of Britain and Norway. The tentacles are arranged in several rows on the margin of the umbrella. In Depastrella from the Canaries there is only one row of marginal tentacles.

Fam. 3. Stenoscyphidae.[[356]]—Stauromedusae with simple undivided umbrella margin. The eight principal tentacles are converted into adhesive anchors. Secondary tentacles arranged in eight adradial groups. Stenoscyphus inabai, 25 cm., Japan.

Order III. Coronata.[[357]]

The external surface of the umbrella is divided into two regions, an aboral region and a marginal region, by a well-marked circular groove (the coronal groove). The aboral region is usually smooth and undivided, but it is an elongated dome, thimble- or cone-shaped, in marked contrast to the flattened umbrella of the Discophora. The margin is divided into a number of triangular or rounded lobes, and these are continued as far as the coronal groove as distinct areas delimited by shallow grooves on the surface of the umbrella. The tentacles arise from the grooves between the marginal areas, and are provided with expanded bases called the pedalia. The manubrium may be short or moderately long, but it is never provided with long lips.

Fam. 1. Periphyllidae.[[358]]—Coronata with four or six statorhabs.

In Pericolpa (Kerguelen) there are only four tentacles and four statorhabs. In Periphylla, a remarkable deep-sea genus from 700 to 2000 fathoms in all seas, but occasionally found at the surface, there are twelve tentacles and four statorhabs. The specimens from deep water have a characteristic dark red-brown or violet-brown colour. They are usually small Medusae, but the umbrella of P. regina is over 21 cm. in diameter. Atorella has six tentacles and six statorhabs.

Fam. 2. Ephyropsidae.—Coronata with eight or more than eight statorhabs.

Nausithoe punctata is a small, transparent jelly-fish, not exceeding 10 mm. in diameter, of world-wide distribution. Its Scyphistoma stage is described on p. [317]. N. rubra, a species of a reddish colour found at a considerable depth in the South Atlantic and Indian Oceans, is probably an abysmal form. Palephyra differs from Nausithoe in having elongated instead of rounded gonads. Linantha and Linuche differ from the others in having subdivided marginal lobes.

Fam. 3. Atollidae.—Atolla is a deep-sea jelly-fish of very wide geographical distribution. It is characterised by the multiplication of the marginal appendages, but the number is very irregular. There may be double or quadruple the usual number of marginal lobes, or an indefinite number. There may be sixteen to thirty-two statorhabs, and the number of tentacles is quite irregular. Some of the species attain a considerable size, the diameter of the umbrella of A. gigantea being 150 mm., of A. valdiviae sometimes 130 mm., and of A. bairdi 110 mm.

Order IV. Discophora.