MARINE MISCELLANEA. 235 



eight and nine inches in diameter, mounted on a short, stout, central supporting 

 stalk or pedicle. In addition to presenting the familiar shallow cup-shaped contour 

 with raised central ridges common to many species, this Turbinaria possesses the 

 notable peculiarity of having the entire outer margin of its rim, to a tolerably uniform 

 depth of two inches, developed downwards and inwards again towards its central 

 axis, in the form of an ornamental frill or border. This revolute edge, which 

 represents the growing margin, is, moreover, decorated with a considerably larger 

 number of vertical ridges than are visible on the upper surface of the corallum. 

 Overlooking the existence of its revolute border, this specimen most nearly resembles 

 the species described in Mr. Bernard's Catalogue under the title of Turbinaria bifrons ; 

 it differs essentially from that type, however, in the relatively minute size and sunken 

 character of the polyps cells or calicles and in other details having a purely technical 

 importance. This specimen, evidently representing a new and hitherto undescribed 

 species, is, pending a full description elsewhere, provisionally associated in this volume 

 with the title of Turbinaria revoluta. 



Shark's Bay can boast of some notable sponges as well as corals. One of the 

 most remarkable of these is figured in the illustration overleaf. By a singular 

 coincidence, the type of this sponge was originally described by the author in the 

 " Proceedings of the Zoological Society for the year 1871," under the name of 

 Caulospongia certicillata. The specimen, while vaguely labelled "Australia," was from 

 an unknown locality, and was placed in the author's hands for description by 

 Dr. J. E. Gray, F.R.S., then Keeper of the Zoological Department of the British Museum, 

 in which Institution the writer was, at that time, an assistant. That originally 

 described type measured but little over a foot in length, and comprised but a single 

 apical cone. The specimen of the same sponge with an authenticated habitat recently 

 added by the writer to the National Collections is upwards of three feet in height, and, 

 in addition to the main central cone, has two smaller ones, each about the size of the 

 original type specimen, symmetrically developed on either side of the central one. This 

 sponge, it may be added, belongs to the so-called " Horny " or " Keratose " group, in 

 which the sponge skeleton is composed mainly of horny matter, after the manner of that 

 of the sponge of commerce, Euspongia officinalis. The striking feature in the present form 

 is that it consists of a central more solid stalk-like axis, around which are developed 

 closely growing flattened whorls or verticils of the finer tissues. The author was more 

 especially indebted for the acquisition of this fine sponge to Mr. Ludwig Stross, a 

 former resident at Fresh Water Camp, Shark's Bay. 



