PENNARIA CAVOLINII. 



365 



portion of hydraiith white, speckled with brown; tliiu apical [loilioii white; gonophorcs \rdh 

 rose red. (Cavoliui.) 



Development of Guiwiiome. — Observed during the siunincr (Cavoliui) and autnnni (Kolliker). 



Habitat. — Attached to rocks in the sea. 



Bathymetrical distribution. — Zone of Cystoseira or Lauiinai'ian zone. 



Localities. — Bay of Naples, Cuvolini; Messina, Kolliker. Gulf of Genoa, Trinchesi. 



Fig. so. 



Though the specific name of disticha assigned by Goldfuss to Cavolini's hydroid may lay 

 claim to priority, I have not hesitated to retain that of Cavolinii, by which Ehrcnbcrg designated 

 the species ; not only because this 

 name has already obtained accep- 

 tance, but because Goldfuss's name 

 is manifestly faulty, for, while claim- 

 ing to possess a specific significance, 

 it is founded on a character which 

 cannot be regarded as specifically 

 distinctive. And in this I feci my- 

 self all the more justified, as the 

 name of one of the most original 

 and accurate observers of the Hy- 

 DRoiDA thus remains connected with 

 an important hydroid form, which 

 he was the first to make known to 

 the zoologist. 



The species of Pennaria are 

 rendered very remarkable by the 

 regular distichous disposition of their 

 primary branches, conferring on the 

 hydrosoma that symmetrical plume- 

 like form which, though the usual 

 condition among the Sertularians, is 

 quite exceptional among the Tubu- 

 larians. 



I have never had an oppor- 

 tunity of seeing a living example of 

 this fine hydroid, of which there has 

 been no complete original description 

 since that of Cavolini, who found 



the species growing upon submarine rocks in the Bay of Naples. I am indebted, however, to 

 Professor Trinchesi, of the University of Genoa, for a well-preserved spirit specimen of what I 

 have no doubt is Cavolini's hydroid. It was obtained in the Gulf of Genoa, and has enabled me, 

 by supplementing the description left us by Cavolini, to frame the diagnosis just given. It has 

 also afforded me the subject from which the accompanying woodcut has seen made. 



Cavolini saw and described the medusiform gonophores, with their umbrella, radiating canals, 



Fragment of a colony of Pennaria CavoVuw 

 preserved in spirits. Magnified about e 



from a specinie 

 jlit diameters. 



