90 Rev. T. Hincks's Contributions towards a 



the present form. The cells are characterized as " pilose " or 

 " covered witli minute pilosities," elongate and narrow, and 

 bitiiberculate above. 



It is said to form large radiating patches on floating weed 

 off the coasts of Patagonia and Cape Horn. 



The diagnosis, after the fashion of the period in which it 

 was published, is brief and insufficient, and the figure is 

 certainly not a correct representation of M. villosa ; but the 

 salient feature of both is the same. The slender spinules 

 covering the membranous front wall, and giving it a pilose 

 appearance, are present in both forms, and, so far as I know, 

 they arc unique. The cells are similar in shape, elongate 

 and rectangular; but in those of F. Isahelleana the side- walls 

 are carried up on each side above into a mucronate process 

 which is entirely wanting in M, villosa. In tliis species the 

 upper margin of the cell is straight and bears on eacli 

 side a tall acuminate spine. There are also a few small 

 lateral spines, which are absent in tiie Cape-Horu species, and 

 also a broad, membranous, strap-like appendage, pointed 

 above, which rises from the centre of the upper margin in 

 many of the cells, and constitutes a curious and very puzzling 

 ])iece of structure. Round the inner edge of the cell there is 

 a line of close-set minute spinules. There are said to be two 

 tubercles on the cell below in d'Orbigny's species, of which I 

 can find no trace in M. villosa. Taking his doscriptiou as it 

 stands we should hardly be justified in identifying the two 

 forms, though it is possible after all that his species may have 

 been founded on examples of M. villosa. 



Ibid. (p. 20 Sep.). 



Memhranipora antiqua, Busk. 



The structure of this species and of others kindred to it had 

 not been thoroughly investigated when my paper was written. 

 We are indebted to Dr. Jullien for a valuable contribution to 

 our knowledge of them and a discussion of their systematic 

 position*. He has founded the genus Onychocclla for species 

 agreeing in general charactcrwith the Mernhranijwra andqua of 

 Busk and tlie family Onyehocellidai for this and a number of 

 related forms. While the structural type is fully and ably 

 defined, an unnecessary number of genera, in my judgment, 

 have been created, and undue stress has probably been laid 



* " Nolo fiur line iu)UV(.'lK' di\ it^i^>n dot; liryozojuros Cheilostcmiont;,' 

 l^ull. de la Soc. Zoologiquo do I'lanoo, t. vi., 1881. 



