MEDITERRANEAN AND NEW-ZEALAND RETEPOE^. 267 



Although Busk has described three species of Retepora which 

 sometimes have barren trabeculse *, they caunot be compared, 

 'with the present form, and the thin shell-structure and the 

 absence of any labial pore or fissure soon showed that it should 

 not be placed with Retepora. The structure of the zooecium 

 being so similar to thac of Palmicellaria, it has been a question 

 whether to call it Palmicellaria parallelata or to create a new 

 genus and name it Farallelata vitrea ; but under either name it 

 can be easily recognized again, and its position determined when 

 more material has been compared. The form of the ovicell is 

 different to any that I am acquainted with in Retepora. 



The disks on the dorsal surface (PI. VI. fig. 11) resemble those 

 on Scrupocellaria, and suggest that rooting processes may be 

 thrown out from these disks, though I find no trace of this in 

 my specimen f, which, though preserved in spirit, had evidently 

 been dead some time, and there were no polypides. 



Living reticulated forms are known in several genera, as 

 Petralia (undatd), Flustra (^crihriformis), Retehornera, several 

 IdmonecB, as 1. Milneana, I. interjuncta, I. Jiahellata, Kirchen- 

 pauer, the last three being joined by barren tubes, while Bugula, 

 reticulata throws out connecting tubes. In the Chalk there are 

 several others ; and when more importance was attached to zoarial 

 characters, the FenestellidcB were classed with Retepora, though 

 they have now long been separated. 



The zoarial resemblance of the species now under consideration 

 to Fenestella will naturally strike any one. The family Fenestel- 



* ' Challenger' Eeport on the Polyzoa, pt. xxx. p. 108. 



t Many instances are known where these disks, or, as we may call them, 

 radic'le chambers, are found in some zooecia without any chitinous tube growing 

 from them. In the Cellulariidis various examples might be cited, and Alysidium 

 Lafontii is a most interesting one, for these radicular disks on the dorsal surface 

 near the distal end have been correctly figured by Savigny, Busk, and others ; but 

 no reference has been made to them, nor does the structure seem to have been 

 understood. These disks are always present ; but, after the examination of a great 

 many specimens, I have only found the rooting-processes growing from one small 

 specimen from Trieste and a small one from the Gulf of Taranto. Dr. A. 

 Keviani, in the ' E.ivista Italian! di Paleontologia ' (April 1895), has published 

 descriptions of two fossils from the Pliocene or post-Pliocene of the Farnesina, 

 which he calls Vibraculina ; and V. Conti, Neviani, is apparently identical with 

 the Naples form, although in the fossil it has not been possible to make out all 

 the structure, and the name Vibraculina would not be suitable, as we now see 

 that there are no vibracula. 



