Zoology.] NATURAL HISTORY OF VICTORIA. [Polyzoa. 



Po)t Phillip Heads, seemingly very rare. 



Easily distinguislied by the smooth zooecia, the anterior vittte 

 and the large gaping avicularia. The lateral process on one side 

 is frequently larger. 



Explanation of Figures. 



Plate ITS. — Fig. 7, anterior surface of portion of branch. Fig. 7a, posterior surface of 

 ame. 



Plate 178, Fig. 8. 

 DIMETOPIA HIRTA (McG.). 



[Genus DIMETOPIA (Busk). (Sub-kingdom MoUusca. Class Polyzoa. Order Infun- 

 dibulata. Sub-order Cheilostomata. Family Eucrateida;.) 



Gen. Char. — Zooecia arranged in pairs united back to back, each pair looking at right angles 

 to that below ; at a bifurcation the zooecia of a pair disjunct, and each giving rise to the first 

 pair of a branch.] 



Description. — Zooecia with the aperture very oblique, narrowed below, slightly 

 arched above, marg-in thickened ; 3 to 5 stiif spines articulated above, 3 or 4 very 

 long, submarginal on each side, the uppermost generally a little farther back and 

 directed more posteriorly, usually 2 spines below. Ooecia globular, surmounting 

 the zooecia. 



Reference.— P. H. McGillivruy, Tr. Roy. Soc. Vict., Nov. 1885. 



Port Phillip Heads. 



Nearly allied to D. cornuta, from which it is distinguished by 

 the diffei'ence in numlier and arrangement of the spines. Of these 

 there are usually 3 short and straight, directed upwards ; on each 

 side there are 3 or 4 very long, articulated immechately beyond 

 the margin, the uppermost being situated a little posteriorly and 

 directed more backwards ; there is a single one or occasionally 

 two below. The ocecium is globular, surmounting a zooecium, and 

 in the specimen figured it is embraced by two long spines, one on 

 each side. I am not certain that this arrangement is constant. 



Explanation of Figure. 

 Plate 178. — Fig. 8, portion of branch, magnified. 



The specimens and descriptions of the interesting Polyzoa on 

 this plate are from Mr. McGillivray. 



Frederick McCoy. 



Vol. II.— Decade XTIII.-2i(. [091 ] 



