Art. TX. — Furtlcer Descriptions of the Tertiary Polyzoa 

 of Victoria. — Part IX. 



By C. M. MAPLESTONE 



(With Plates XVI., XVII.). 

 [Eead 2nd July, 1903]. 



Dimorphocella, nov. gen. 



Two distinct forms of cells. Zooecial cells elongated or rhom- 

 boidal, distinct. Thyrostome arched above, with a sinus in the 

 lower lip. Ooecial cells much larger than the zooecial, elongate, 

 pyriform or oval, with a broad aperture and a perforated area in 

 front. 



I propose this genus for a form presently to be described, and 

 Adeonella triton, McG., the systematic position of which he 

 (Dr. MacGillivray) says admits of great doubt.^ I do not con- 

 sider it belongs to the genus he places it in, if his definition of it 

 given in his catalogue of the Marine Polyzoa of Victoria, p. 27, 

 be accepted. Busk iu the Report of the "Challenger" Polyzoa, 

 <lescribes Adeoneae as a new family which he divides into two 

 genera, Adeona and Adeonella, but the characters upon which he 

 separates them are purely zoarial, and moreover, he states, 

 " there is no difference whatever " in the zooecial characteristics 

 of the genera. Consequently, as zooecial characteristics are 

 more relied upon now than zoarial, the genus Adeonella I think 

 must lapse. Dr. MacGillivray places Adeona in Microporellidae, 

 and Adeonella in Escharidae, sub-family Mucronellinae, in his 

 " Catalogue," and in his INIonograph of the Tertiary Polyzoa of 

 Victoria he places Adeonella in Schizoporellidae, but does not 

 define it. Again, in the description of Adeonella, in the 

 " Catalogue " the following character is mentioned, " peristome 

 developing a piocess from each side below, the two meeting in 

 the middle to leave a round suboral foramen opening into the 

 throat in front of the operculum." Now, no mention is made of 

 such a character in the specific description of A. triton, it is not 

 shown in the figures (pi. ix., figs. 23 and 23^\ and this charac- 



1 Trans. Royal Society Victoria, vol. i\'., p. 90. 



