290 Descriptions of New, 



interspaces thicker than in younger ones. The form of the 

 lower lip varies ; it is usually straight and entire, with a 

 rounded avicularium immediately below ; sometimes there is 

 a slight fissure in place of the avicularium, and occasionally 

 there is a fissure towards one side, and on the wider part of the 

 lip an avicularium. In young marginal cells there is no 

 appearance of any sinus. In one specimen, which I was in- 

 clined at first to refer to a distinct species, the fenestras are 

 very long, and are formed by the irregular anastomoses of 

 branches from a main stem. The cells are longer, the 

 separating raised margins not so prominent, the avicularia 

 not so regularly placed, and many of the oral spines, of 

 which in the marginal cells there are frequently four or five, 

 present the same telescope-like appearance as is seen in 

 R. rnonilifera. The back is smooth, the vibices not so 

 prominent, the enclosed spaces not so angular, and each with 

 a small round avicularium near its centre. In another older 

 and somewhat worn specimen, in which the mode of branch- 

 ing is precisely similar, many of the cells present the 

 characters of the typical form. 



» 



Retepora granulata, M'G. Fig. 7. 



Polyzoary massive, convoluted. Fenestras rounded, small, 

 much narrower than the interspaces. Cells elongated, sepa- 

 rated by narrow raised lines ; mouth arched above, straight 

 below ; lower lip with a narrow vertical sinus, on one side 

 of which is a rounded avicularium ; surface of cells granular 

 or tuberculate ; numerous small oval avicularia scattered 

 over the cells, and a few larger situated on rounded eleva- 

 tions. Ovicells large, rounded, granular. Back of poly- 

 zoary granular, vibicate, with small, scattered, rounded 

 avicularia. 



Port Phillip Heads. 



Of this, the most massive species with which I am 

 acquainted, I have one perfect specimen four inches high, and 

 of the same width at its widest part. It is attached by a 

 stout calcareous basis. The polyzoary is very thick, foliaceous, 

 twisted, and united so as to form several calyculate cham- 

 bers. It is of a brownish colour (dried). The other speci- 

 mens I have are mostly fragments. In addition to the usual 

 granulations over the surface, in many cases there is a row 

 forming small processes on the upper margin of the mouth. 

 The young ovicell is fissured, the fissures becoming filled in 



