A MONOGRAPH OF THE TERTIARY POLYZOA OF VICTORIA. 07 



avicularium on the outer side close to the tliyrostome, the mandible pointed 

 downwards and inwards, the sides niucli raised, and the wliole forming a con- 

 siderable proiection ; another small avicularium on a distinct elevation external to -,7.7 -. 

 this and on a lower level. -^'^ " ''*■ 



S.P. ; M.C. <tUzn_}^'^ 



In this very peculiar form the thyrostomc is Lepralian, but tlie peristome is 

 very much elevated and appears, owing to its deficiency below, like a short tube 

 with a slice cut out of the lower side, the upper part having a hood-like appearance. 

 The avicularia are arranged in a manner quite different from what is found else- 

 where. There arc two on the external side of the tliyrostome. One is close to it 

 and has its inner side incorporated with the peristome ; the other is separated and 

 situated externally, reaching close to the junction of the zoarial lamina. These 

 external avicularia are arranged almost in a special tract, sej)arated from the 

 corresponding series of tlie other lamina by a slight ridge, tliose of the two series 

 being opposite to each other. 



Pachystomaria, n.g. 



Zoarium unilaininate. Zooecia broad above, narrowed belo\A', oblique ; surface 

 cribriform ; tliyrostome rounded or elliptical ; peristome much thickened, entire, 

 and, as well as the portion of the zooecium immediately lielow and to the sides, 

 elevated ; in the only species a large triangular avicularium to one side of the 

 tliyrostome. 



1. F. pari-qniiicfa, n.sp. PL VIII., fig. 24. 



Zooecia in obscurely radiating series, wide above, narrowed below ; surface, 

 except above, perforated by numerous small, close-set round pores, the margin 

 forming a slightly thickened rim ; upper part, immediately below and to the sides of 

 the tliyrostome and avicularium, raised, and with a few large irregular rounded or 

 elongated pores ; tliyrostome transversely elliptical, the peristome much thickened ; 

 a large broad avicularium, with triangular mandible directed upwards and outwards, 

 below and to one side of the tliyrostome. 



M.C. 



Of this very interesting species I have only two incomplete but well-preserved 



specimens. They are both unilaminate, convex anteriorly and concave posteriorly. 



The zorecia are arranged in an irregularly radiating manner. In one sjiecimen the 



dorsal surface is formed by radiating series of conv(^x ridges, with a few pores or pits 



contracted at intervals and separated by deep grooves, exactly similar to tlie 



structure found in many species of Selenaria and Lunulites. In the other the 



o 



