188 A Catalogue of the 



The list, long as it is (induding about 350 species), will 

 certainly be very much added to. The only locality which 

 has really been systematically searched is the neighbour- 

 hood of Port Phillip Heads, which has been dredged by 

 Mr. Wilson and myself. Mr. Wilson has also spent some 

 time dredging in Western Port, principally at the entrance, 

 and Mr. Maplestone has dredged at Portland. The speci- 

 mens from other localities have been collected on the 

 beach. 



It is hoped that the arrangement followed here will be 

 found, at least, convenient. 



For the classification of the Polyzoa all naturalists are 

 now agreed that the zooecial characters are of primary im- 

 portance. At the same time, the zoarial, when constant, 

 demand consideration, and in the Cyclostomata, owing to 

 the little variety in the structure of the individual zooecia, 

 we are obliged to depend to a great extent on them. Of 

 the zooecial characters, among the Cheilostomata, the prin- 

 cipal are tiie amount of calcification of the cell-wall, the 

 presence or absence of special pores communicating with 

 the body cavity, the form of the mouth (primary and 

 secondary) with the structure of the operculum, the nature 

 and situation of the ooecia, and the avicularia or vibracula. 

 The form and structure of the mouth, including the oper- 

 culum, undoubtedly afford one of the most constant and 

 easily used means of diagnosis. The structure of the 

 operculum, to the value of which attention was first drawn 

 by Mr. Waters, has already proved of great assistance in 

 the discrimination of the species of Cellaria, Cellepora, 

 Retepora and other difficult genera, and there can be no 

 doubt that much more use will be made of its characters 

 than has hitherto been done. To the presence of special 

 pores on the front of the zooecia much importance must 

 be attached. By special pores I mean the true pores 

 found in the Microjporellidce, &c,, opening directly into 

 the body cavity. These are to be carefully distin- 

 guished from those which are formed by an outgrowth of 

 the peristome on each side, overarching and meeting in 

 the middle, leaving a pore opening into the peristomial 

 cavity outside the true mouth, as in Porina and Adeonella. 

 In old or highly calcified specimens of the latter genera it 

 is often difficult or impossible to see the real structure, but 

 in the growing edges the formation of this external or 

 adventitious pore can be easily traced. It also occurs 



