XII STAUROMEDUSAE CORONATA 32 1 



off the coasts of Europe and North America, extending south into 

 the Antarctic region. 



Lucernaria differs from Haliclystus in the absence of stato- 

 rhabs. It has the same habit as Haliclystus, and is often found 

 associated with it. L. campanulata is British. 



Halicyathus is similar in external features to Haliclystus, but 

 differs from it in certain important characters of the coelenteric 

 cavities. It is found off the coasts of Norway, Greenland, and 

 the Atlantic side of North America. 



In Capria, from the Mediterranean, the tentacles are replaced 

 by a denticulated membrane bearing nematocysts. 



The rare genus Tessera, from the Antarctic Ocean, differs from 

 all the other Stauromedusae in having no stalk and in having 

 only a few relatively long non-capitate tentacles. If Tessera is 

 really an adult form it should be placed in a separate family, 

 but, notwithstanding the presence of gonads, it may prove to be 

 but a free-swimming stage in the history of a normally stalked 

 genus. 



Fam. 2. Depastridae. — The margin of the umbrella is pro- 

 vided with eight shallow lobes bearing one or more rows of 

 tentacles. Statorhabs absent. 



Bepastrum 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.^ — Stauromedusae with simple un- 

 divided umbrella margin. The eight principal tentacles are 

 converted into adhesive anchors. Secondary tentacles arranged 

 in eight adradial groups. Stenoscyphus inahai, 25 cm., Japan. 



Order III. Coronata.^ 



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, 



^ Kishinouye, Journ. Coll. Sci. Tokyo, xvii. 7, 1902. 



^ A discussion of the classification of this order occurs in Vanhbffen, " Aorasped. 

 Med. d. deutschen Tiefsee Expedition," iii. 1902, p. 49. 



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