ALDINGA AND THE RIVER-MURRAY CLIEFS, SOUTH AUSTRALIA. 281 



made a generic test, and the tendency still remains to attach great 

 weight to their absence ; but the instances furnished in this and 

 former papers show that great caution is necessary here, though 

 certainly when present they furnish characters of the greatest value. 

 Their presence also often materially changes the general appearance 

 of the colony, and no doubt many reductions of supposed species will 

 have to be made, just as entomologists have frequently found that 

 the male and female insects have received different names. We 

 ought now to give greater attention to the nature of each character 

 than to the general appearance of the zoarium, which often super- 

 ficially varies greatly when young or old and from different depths. 



Since my last paper was published the most valuable and interest- 

 ing ' Report ' on the ' Challenger ' Bryozoa has appeared, in which, 

 as we expected, Mr. Busk puts into our hands a series of splendid 

 illustrations and concise descriptions. In this place we can only 

 consider tnose parts which have a bearing upon the fossils found in 

 Australia, and the number of representatives of this fossil fauna is 

 not so large as we expected, but we find Porina coronata, E.ss. 

 {Eschar a gracilis, Busk), Schizoporella phymatopora {Myriozoum 

 Jionolulense, Busk), Gellepora alhirostris, O. tridenticulata, and Mono- 

 porella crassatina, W., all of which seem to have been common 

 fossils. It will be seen that the generic names used are not in every 

 case the same ; and we may point out that Mr. Busk has, of course, 

 abandoned the classification which he found it convenient to adopt 

 thirty-two years ago, before the labours of Smitt, Hincks, and 

 others had shown that the zooecial characters must be taken as of 

 most importance. It is not, however, astonishing that Mr. Busk 

 should now and then show a predilection for a style of classification 

 not quite in accordance with the thorough changes which some of 

 us feel must be adhered to ; but these are now matters of detail, 

 as the main modern principles are recognized, and we may say all 

 leading authorities are now working in the same direction. 



As instances, the divisions of the families Membraniporidae and 



sardonica, W., from the Meditei-ranean, and in C. corotwpus, C. retusa, var. 

 caminata, and other species. Mr. Busk {loc. cit. p. 90, note) seems to have 

 looked in vain in C. sardonica for it ; but perhaps he only examined the oral 

 avicularia, in which none are to be found, whereas in the small semicircular 

 mandibles it is i-eadily distinguished. On referring to a drawing of a mandible 

 made when describing C. sardonica some years ago. I find that there is a large 

 columella shown, and upon reexamination I find them iisually quite distinct, 

 though in some other species they are but rudimentary. In many species there 

 is a denticle in this position rising from the calcareous bar which divides the 

 avicularium, and this is shown in my figure of C. sardonica (Ann. & Mag. Nat. 

 Hist. ser. 5, vol. iii. pi. 14. fig. 5), and maybe seen in C. alhirostris, C. tridenti- 

 culata, various BetejporcB, Lepralia edax, &c., being by no means confined to 

 Cellepora. It is thus Seen that it may sometimes be a useful character in de- 

 termining fossils. The mandible of Diachoris magellanica, Busk, has a double 

 " columella." I think that it will be found that what Mr. Busk describes as 

 " short hairs " on the columella are only the remains of the attachment of mus- 

 cular threads. The subject of the avicularian mandibles I have dealt with 

 more fully in a paper which will appear in the Journal of the Royal Micro- 

 scopical Society, ser. 2, vol. v. pt. iv. 



