of the Hydroida of the Adriatic. 



121 



It appears, then, that in the Adriatic there is a considerable 

 group of PlmnxdaricB distinguished from one another by com- 

 paratively slight differences, most of which have not hitherto 

 been noticed elsewhere. 



Laomedea dichotoma. — The description given of this species 

 is not sufficient for identification ; and in the absence of any 

 reference to the later writers, who have most carefully inves- 

 tigated the Campanulariidge, it is impossible to decide what 

 form is intended. 



Laomedea gelatinosa. — The brief diagnosis and the reference 

 in the synonymy to Johnston's plate xxv. figs. 3, 4, would 

 seem to show that the Adriatic species to which this name is 

 applied is the Campamdaria flexuosa^ Hincks. It is certainly 

 not the Laomedea ( Obelia) gelatinosa of Pallas. 



Camj)anida7'ia voluhilis. — The Campanularia {Clytia) 

 Johnstoni of Alder is, no doubt, the species intended. The 

 description shows that it is not the C. voluhilis of Linnaeus. 



To sum up, of the 37 species of Hydroida recorded by 

 Prof. Heller as occurring in the Adriatic, two {Coryne 

 jnisilla and Laomedea dichotoma) cannot be identified with 

 any certainty ; of the remaining 35, 18 are also found in the 

 British seas. The list of species that are common to Great 

 Britain and the Adriatic, as now revised, is as follows : — 



Eudendrium ramosum. 

 Tubularia indivisa. 



lar\Tix. 



Haleeium halecinum. 

 Sertularella polyzonias. 

 Sertularia abietiua. 



operciilata. 



Dipliasia tamarisca. 



attenuuta. 



Thuiaria articulata. 

 Antenmilaria antennina (?). 



[It 



is not improbable that A. Ja- 



nim was tlie species recorded 



by Olivi under this name.] 

 Aglaophenia pluma (cristata, 



Heller). 

 myriophyllum. I have this 



species also from the Red Sea. 

 Plumularia frutescens. 

 Obelia genicidata. 

 Campanularia flexuosa. 

 Clytia Johnstoni. 

 Lafoea dumosa. 



Of the foregoing, Sertularella polyzonias and Sertulai-ia 

 opercidata are cosmopolitan species. 



Of the remaining 17 species contained in Prof. Heller's list 

 six are new, and ^o far have only been found in the Adriatic ; 

 and five of the six are referable to the genus Plumularia. 

 The rest are known Mediterranean and Adriatic forms. 



I hope that Prof. Heller may continue his researches, and 

 give us a much fuller account of the Hydroid fauna of this 

 interesting district. 



Ann. d: Mag. N. Hist. Ser.4. Vol.\x. 



