Zoology.] NATURAL HISTORY OF VICTORIA. [Poli/zoa. 



it is also traversed by various tliickened lines or bands, much 

 less prominent in the fii'st. In T. Woodsii and disjMr it is 

 crossed, a little below the mouth, by a transverse or oblique 

 fissure, the edges of which are finely denticulated. The true 

 Micropor(s, to which the genus- is most nearly allied, agree in 

 having a calcareous anterior wall covered by a thick epitheca, 

 with the lower margin of the oral aperture thickened and the 

 lip formed by a complete articulated flap. The form of the 

 mouth, however, is quite different ; in Thairopora it is very 

 much loftier and narrower and always has a thick, calcareous, 

 sessile, mamilliform or bullate process in a separate space on 

 each side, frequently differing in size ; while in Microjfora the 

 mouth is wider than high, and there are either no oi'al processes 

 or they are slender articulated spines. 



The peculiar dividing lines or fissures on the calcareous 

 front walls are quite different fi'om anything seen in Micropora. 

 I am not sure that it would not be advisable to separate the 

 species Avith the transverse fissures as a distinct genus. A 

 similar division exists also in Diploporella cincta, which also 

 agrees in the form of the mouth and operculum and the 

 pi'esence of the thick sessile oral pi'ocesses. The structure of 

 the zooecium, however, is otherwise so distinct as to leave no 

 doubt of the propriety of referring it to a distinct genus. 



Plate 196, Figs. 4, 5, and 6. 

 MICROPORA CORIACEA (Esper. sp.). 



[Genus MICROPORA (Hincks). Sub-kingdom Mollusca. Class Polyzoa. Order 

 Infundibulata. Sub-order Cheilostomata. Family Microporidse.) 



Oen. Char. — Zooecia with the front wall calcareous, covered with a thick epitheca; no 

 transverse bands or fissures, but frequently several large perforations. Mouth with lower lip 

 straight and thickened, wider than high ; lower edge of operculum straight ; oral spines either 

 wanting or slender and articulated. Ooecia external. Avicularia at the base of zooecia.] 



Vol. II— Decade .XX.— 3(i. [ 353 1 



