or Little Knoivn, Polyzoa. 289 



triangular projection pointing upwards; a long spine articu- 

 lated on each side of the mouth. Numerous large avicularia, 

 the rostrum elevated, and with strong curved beak, the 

 mandible triangular and pointed. Ovicell rounded, widely 

 open below, crossed by an obscure ridge. Back smooth, 

 vibicate, with scattered avicularia, with triangular man- 

 dibles. 



Off Port Phillip Heads. 



Of this elegant species I have only one complete specimen. 

 It is three-quarters of an inch in length, by half-an-inch at 

 the broadest part, and forms a slightly convoluted, leaf-like 

 polyzoary. I have also three or four other fragments, which 

 all present the same character. The small, central, suboral 

 avicularium, with the triangular process on each side, is 

 very characteristic. In place of the avicularium there is 

 frequently a loop-shaped opening, no doubt formed by the 

 destruction or loss of the chitinous part. The ovicell also is 

 very distinct from that of any other species, and the hu^e 

 avicularia, situated on the front of many of the cells, form 

 very striking objects. 



Retepora porcellana, WG. Fig. 9. 



(R. robusta, Hincks, Ann. and Mag. iV. Hid., May, 1878.) 



Polyzoary massive, expanded, convoluted, or calyculate. 

 Fenestras elongated, narrower than the interspaces. Cells 

 separated by distinct raised lines, terminating superiorly 

 opposite the lower part of the mouth ; mouth arched above, 

 straight or slightly hollowed below ; lower lip entire, with 

 (usually) an avicularium immediately below it; a spine 

 articulated on each side; an elliptical avicularium on the 

 front of the cell toward the lower part, directed straight or 

 obliquely downwards. Ovicell rounded, smooth, entire, not 

 much projecting ; when young with a broad, short, vertical 

 opening, which, as growth advances, becomes filled in, and in 

 some cases forms a prominent ridge. Posterior surface 

 obscurely granular or slightly areolated, traversed by 

 numerous raised lines, and usually with one or more small 

 oval avicularia situated on each part defined by these 

 vibices. 



Port Phillip Heads and elsewhere. 



Varies a good deal in appearance, according to age, old 

 specimens being very massive, the fenestras shorter and 



v 



