of the Ilydroulu of the Adriatic. 119 



the reference to Johnston's fig. 12, c,d, p. 72), should be as- 

 signed to Dipliasia attenuata^ mihi, a species which has oc- 

 curred at Port Adelaide as well as on the British coasts. 

 Heller seems to have met with the female gonotheca only, 

 which he rightly describes as much attenuated below, and 

 above covered with numerous spines. 



Thidaria lichenastrum. — This species is recorded by Olivi 

 as a native of the Adriatic ; but Heller considers it probable, 

 from the description given of it, that the form intended should 

 be referred to the T. articulata^ ' Pallas. The Sertularia 

 liclienastrum of Linnaeus is closely allied to the latter ; but 

 Pallas, who had seen specimens from Ceylon exactly answer- 

 ing to Linnajus's description, considered the two forms di- 

 stinct. It seems probable that the Adriatic species is identical 

 with our British articidata. 



The genus Plumularia Prof. Heller subdivides into three : 

 he retains Lamarck's name for the P. pluma section, in which 

 the nematophores {^^ Nebenzellen " of Heller) are developed only 

 in connexion with the calycles, and the latter are approximate, 

 and adopts Donati's Anisocalyx for the group in which the 

 nematophores are generally distributed, the calycles compa- 

 ratively distant, and long and short internodes alternate on 

 the branches. For the section in which the shorter inter- 

 mediate internodes are wanting he proposes a new genus, 

 under the name of Heterojpyxis. But the character relied upon 

 as a generic distinction in this latter case is quite insignificant. 

 Of the most intimately allied species (e. g. Plumularia echinu- 

 lata^ Lamk., and P. similis, Hincks), some possess the inter- 

 mediate joint, and some want it. Of the two British species 

 oi Antennulari'a, antennina has it, but it is not present in 

 ramosa. The difference is of the most trivial kind, and should 

 have no place in a generic diagnosis, much less should it 

 stand as the chief criterion of a genus. Nor can I agree with 

 Prof. Heller when he adopts T)o\\nX\' & Anisocalyx for the group 

 in which the nematophores are distributed over the stem and 

 branches. The nomenclature of the Italian naturalist (who 

 regarded the zoophytes as plants) has not obtained any currency 

 in the literature of the Hydroida ; and the particular name in 

 question seems to have had no reference originally to this 

 section of the PluimdarUdw, but to have been applied to cer- 

 tain forms belonging to the other group, of which the Sertularia 

 pluma (Linnaeus) is the type. Under these circumstances it 

 seems to me better to retain the two well-known and widely 

 used names of Lamouroux and Lamarck, Aglaoplienia and 

 Plumularia. Meneghini assigns the name Anisocalyx to a 

 genus which he has founded for the Sertularia secundaria 



