and on Urceolipora, a New Genus of Polyzoa. 87 



It is of an ash-grey colour. The fenestra are small, 1 to 

 2 mm. in diameter, the intervening spaces 3 to 4 mm. ;wide. 



The cells are expanded and arched above, narrowed below, 

 surface pitted, the pits forming a regular row just inside the 

 margin. Surface raised round the mouth. Mouth nearly 

 circular. A round pore a short distance below, to the 

 side of which is frequently attached a minute triangular 

 avicularium, with the mandible pointed obliquely upwards. 

 The surface immediately round the fenestra is not divided, 

 but forms a narrow, continuous, punctate rim. Around this 

 rim are usually four or five large avicularia, replacing cells. 

 In these the mandible is very wide at the base, rapidly 

 narrowing to a long, slender point. 



Port Phillip Heads, Mr. J. B. Wilson. 



The species of this genus now known to occur in Victoria 

 are D. cellulosa,, D. grisea, D. Wilsoni, and D. albida var 

 avicularis. They are all readily distinguished from each 

 other. D. cellulosa has been figured and described in the 

 Decades. D. grisea, of which a beautiful specimen was 

 dredged by Mr. Wilson off Port Phillip Heads, is closely 

 allied to it, but may be distinguished by the polyzoary being 

 simple and fan-shaped, or only slightly proliferous, and by 

 the mandible of the avicularium being shorter, broader, and 

 directed obliquely across the front of the cell, not, as in 

 D. cellulosa, extending up the side of the cell to opposite the 

 middle of the mouth. In D. grisea, also, there is a wart-like 

 elevation, situated on the side opposite to that to which the 

 avicularium points. D. cellulosa and grisea, in addition to 

 having much larger avicularia, differ from the other two in 

 the structure of the margin of the fenestras. In the two 

 former it is divided into prominent nodules, like abortive 

 cells, while in the latter it is thin, and not so divided. When 

 the ectoderm covering the cells is removed by incineration in 

 a spirit lamp, the calcareous pattern is seen to be distinct. It 

 is difficult to describe the differences in words, but, as the 

 appearances will be of value in determining any fossil species, 

 they will be carefully figured in the* Decades. 



Explanation of Plate. 



Fig.l. Catenicella concinna, front. Fig. la. Back of cellxGO. 



Fig. 2. C. Wilsoni, front. Fig. 2a. Back view. Fig. 2b. 

 Ovicell x 60. 



Fig. 3. Jlrceolipora nana x 25. Fig. 3a. Front view of a 

 cell and ovicell. Fig. 3b. Lateral view of a portion of a 

 branch x GO. 



