776 Transactions of the Society. 



the number of described mandibles by giving tbe figures of some 

 in my collection, and as these are mostly from Mediterranean 

 species, this must be considered as another supplement to the 

 description of species from the Bay of Naples. 



In the communication referred to, I said, when speaking of the 

 Celleporidse, that " I believe the opercula may assist very much to 

 bring this family out of its present confusion," and Mr. Busk has 

 now made a good start towards making this a fact. There is, 

 however, one point connected with the Cellepora mandibles which 

 requires further notice, as Mr. Busk describes a slender process 

 rising from the middle of the base of the avicularian mandible in 

 the holes tomatous division of the genus Cellepora, but finds it only 

 in this division, and further only in those from the southern hemi- 

 sphere. In a paper read before the Greological Society I have 

 shortly pointed out that this is by no means the case, but that it 

 can be found in species from the northern hemisphere, not only in 

 both divisions of this genus, but apparently in other genera. Mr. 

 Busk seems to have looked for it in vain in Cellepora sardonica 

 Waters, from the Mediterranean, but this species has two forms of 

 avicularia, one triangular and acute (fig. 39), in which I do not 

 find any process, whereas in the small round avicularium (fig. 33) 

 this process is very distinct, so that perhaps Mr. Busk only ex- 

 amined the one form. Besides occurring in this species of Cellepora 

 it is found in Cellepora coronopus Woods (fig. 29) and C. costata 

 MacGr. (fig. 31).* In a similar position there is in many species a 

 process arising from the calcareous bar which divides the aperture 

 of the avicularium. This I figured six years ago in C. sardonica 

 (loc. cit. plate XIV. fig. 5), also in ScMzoporella hiaperta (id. 

 plate XI. fig. 1). Smitt also figured it in the avicularia of Lepralia 

 edax (Floridan Bry., plate XI. fig. 222), and it is a character 

 which can frequently be distinguished in well-preserved fossils (see 

 fig. Befepora marsupiata var., Q. J. Geol. S,, vol. xxxix. plate XII. 

 fig. 21). It occurs in Schizoporella auriculata, Porella cervi- 

 cornis, Rete'pora Couchii, a New Zealand Smittia, &c. 



The process in the chitinous mandible Mr. Busk calls a 

 columella, and says that it is covered with " short hairs," but these 

 upon comparison with other mandibles turn out only to be the 

 remains of the attachment of the muscular threads. 



In the ' Challenger ' report a genus Adeonella was made, and 

 includes species having a pore opening into the body of the zooecia 



* The mandible of Diachoris magellanica B. (fig. 4) has a double " columella," 

 and since the paper was written the examination of D. hilaminata Hincks, shows 

 that the mandibles of both are identical in size and detail structure, and the 

 similarity of other specific minute characters is most close, proving that the two 

 species are most closely allied, although the mode of growth produces a very 

 different general appearance. 



