72 Rev. T. Hincks's Contributions towards 



no calcareous lamina ; spines none. Avicularia resembling 

 the ordinary zooecia in form, sometimes rather smaller, occa- 

 sionally elongated and narrowed, interspersed among the cells; 

 mandible rounded. Ooecium somewhat depressed in front, 

 smooth and glossy. 



Loc. Madeira (J. Y. ,/.). 



In this fine species the cells are distinguished by their 

 regularity of form, their depth, and the broad strongly cre- 

 nated borders. The avicularia are remarkable for their close 

 resemblance to the ordinary zocecium; in dead specimens they 

 are only distinguishable from it by the stout calcareous bar 

 which crosses the area, and on which the mandible works in 

 the living state. They are probably amongst the simplest of 

 the " primary " forms *. 



Membranipora granulifera, n. sp. (PL IX. fig. 4.) 



Zooecia irregular in shape, usually expanded towards the 

 bottom and somewhat narrowed at the top ; area surrounded 

 by a slightly raised smooth edging, the lower portion filled 

 in by a minutely granular calcareous lamina, which is carried 

 up on each side of the aperture ; aperture obscurely trifoliate. 

 A pair of acute avicularia above it, one placed on each side, 

 the mandibles directed towards one another. 



Loc. Madeira (J. Y. J.). 



In what seems to be the normal condition the zooecium is 

 broad below and becomes narrower towards the top ; but the 

 cells are closely packed together, and there are considerable 

 differences in the shape, which are, no doubt, due to this cir- 

 cumstance; not unfrequently the lower extremity is produced 

 and pointed. A smooth marginal line encloses the area, 

 which, with the exception of the subtrifoliate aperture, is 

 filled in by a beautifully beaded or granulous plate. The two 

 avicularia at the top of the aperture constitute a striking- 

 feature, and are constantly present ; they are somewhat 

 raised, and are placed one on each side, close to the margin, 

 their pointed extremities directed towards one another and 

 frequently meeting in the centre. There is a total absence of 

 spines in the specimens which I have examined. The species 

 belongs to the M. Flemingii group, but is a very well-marked 

 form. 



* I have ranged the avicularia under three classes — the primary, ex- 

 hibiting the smallest amount of differentiation, the secondary or transi- 

 tional, and the articulated (Hist, of Brit. Mar. Polyzoa, Introduction). 



