32 2 COELENTERATA SCYPHOZOA chap. 



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.^ — Coronata with four or six stato- 

 rhabs. 



In Fericolpa (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. 7'egina 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. H. ruhra, a species of 

 a reddish colour found at a considerable depth in the South 

 Atlantic and Indian Oceans, is probably an abysmal form. 

 PaUphyra differs from Nausithoe in having elongated instead 

 of rounded gonads. Linantha and Linuche differ from the others 

 in having subdivided marginal lobes. 



Fam. 3. AtoUidae. — 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. 



' The Periphyllidae constitute Haeckel's order Peromedusae. 



