HYDROIDA 



fact, rather rare and scattered, is bound to substrata of stones, which may be, at a pinch, replaced by 

 the shell of a Mytilus, while the colonies luxuriantly developed of the forma squamata are resident on 

 the leaves of the Fucoideae, where certainly the supply of food is much more copious. 



The description of Forskal (1775) being older than that of O. F. Miiller (1876), we have 

 according to the rules of nomenclature in force, to drop the specific name employed by the latter, 

 Clava squamata and to maintain the denomination bestowed on the species by Forskal, Clava multi- 

 cornis. Its limitation from the American species Clava Icptostyla L,. Agassiz, has not as yet been 

 ascertained, and it seems on the whole questionable if the two species are really to be distinguished. 



Clava nmlticornis is a boreal species, which seems, nevertheless, to be able to penetrate far 

 into the Mediterranean (Babic 1904). It is a littoral form, and forma squamata has been found only 

 in the tidal zone; forma genuina, on the other hand, at rare intervals, has been met with a little ben- 

 eath the tidal zone in places with rather small salinity. Fabricius (1780) records the occurrence 

 of the species at Greenland without particular statement of locality; however, it has not afterwards 

 been observed in this place. On the other hand, the species seems to occur not unfrequently on the 

 south west coast of Iceland. It is frequently met with at the Faroe Islands, and is found everywhere 

 round the British Isles and on all coasts round the North Sea. Its occurrence at the northern parts 

 of the coast of Norway is not sufficiently accounted for, but does not seem to be particularly frequent. 



Gen. Merona Normann. 



From the reptant stolons arise unbranched, chitinous polyp stems. In the upper part of the 

 stem the perisarc is so wide that the polyp can be retracted into it, though developement of a hydro- 

 theca is not indicated. The filiform tentacles are irregularly spread over the polyp. The gonophores 

 are borne upon reduced polyps (blastostyles) arising from the reptant stolons. 



With great hesitation I set up Merona as a genus of its own. It is distinguished from Cory- 

 dendrium van Beneden (1844) only in mere trifles of no great importance. Thus its polyp stems 

 are unbranched, while the hydrocaulus of Corydendrium is richly branched. Another distinguishing 

 character may perhaps be sought in the quality presented by Merona in its wide perisarc, into which 

 the polyps are retractile. But none of these criteria can be said to be of properly generic value. When, 

 nevertheless, Merona is provisionally maintained, it is due to the fact that only an exceedingly scarce 

 material of a single species is in hand, and that the state of preservation of this material allows of 

 no closer inquiry into the polyps. 



Merona cornucopiae Norman. 



1864 Tubiclava cornucopiae, Norman, On undescribed British Hydrozoa, Actinozoa and Polyzoa, p. 357. 



1865 Merona Norman, On Merona, an undescribed genus of British Hydrozoa, p. 262. 



The hydrocauli are unbranched and attain a height of about 5 mm.; the stems are narrowest 

 at the base and increase gradually in diameter till they attain their greatest width closely below the 



