A MONOGRAPH OP THE TERTIARY POLTZOA OP VICTORIA, 81 



forwards or occasionally obliquely to one side ; thyrostome semicircular, lower lip 

 straight, with a small sharply-defined rounded sinus ; peristome thickened ; 

 surface finely granular and sometimes perforated ; an avicularium, with broadly 

 triangular or rounded mandi])le, usually on one side about the middle, directed 

 outwards or obliquely upwards. Ocecia large, slightly prominent, immersed in the 

 zooecium above. 



S.P. ; M.C.; C.B. ; B.E.; M. ; C.C. (W.). 



There are usually four or six rows of zocecia in a cylinder. In one specimen the 

 zoarium is in a single layer. In some the avicularia are absent. 



3. S. playiostoma, v,.'^\). PI. XI., fig. 4 



Zoarium in cylindrical form probably from having encrusted narrow algae. 

 Zooccia much elongated, quadrate, slightly narrowed below, arranged in transverse 

 or spiral series, with distinct raised margins; surface finely granular and perforated ; 

 thyrostome situated obliquely in an ujoper angle of the zoa'cium, broad, lovrer lip 

 straight, with a small rounded sinus, peristome on upper edge slightly thickened. 



S.P. ; B.E. ; C.B. ; M. 



The zocecia are arranged in a slightly oblique and transverse manner, and in 

 the complete cylinder would probably be spiral. It differs from S. plujmatopora in 

 the quadrate form of the zocecia, and especially in the peculiar position of the 

 oblique thyrostome in an upper angle of the zooecium. In some specimens, as in 

 that figured, there is an avicularium on one side, close to the margin, with the 

 triangular mandible directed straight upwards. In these also the anterior extremity 

 is not so quadrate, but is rather acuminate, and the whole turiied to one side. 



4. S. lata, McG. PI. XI., fig. 5. 



Schi sopor ella lata, McG., P.Z.V., 138 ; f S. marsupifera, Busk, C.P., p. 165. 



Zoarium crustaceous. Zocecia arranged in linear series or irregularly, quadrate 

 or ovate, with distinct raised margins ; surface granular or granulo-punctured ; 

 thyrostome rounded above, contracted below, with a rather wide sinus ; below the 

 sinus an avicularium with the mandible directed downwards. 



B. Living. Australia. 



The size of the avicularium varies, being sometimes quite small and situated on 

 a slight elevation, at other times long and narrow. It is allied to ;S'. triangula 

 (Hincks) Ijut differs in the thyrostome being rounded above and not triangular, as in 

 that species. Both are common, living at Port PhiUip Heads. 



M 



