190 A Catalogue of the 



Gallopora. Ainphihlestrwiin, although a convenient genus, is 

 not satisfactory. There is a wide difference, for instance, 

 between A punctigerum, with only a minute portion of the 

 corners of the area filled by a membranous thickening, and 

 A. argenteumi or pevQiiunitibm, where a large portion is 

 occupied by a calcareous lamina. It would probably be 

 better to refer the latter forms to a distinct genus. I am a 

 little doubtful about the propriety of my genus BoMiypora, 

 but the species is not easily referable to any of the other 

 divisions. 



In the MicToporida3 I have included those Membrani- 

 poridan genera having the opercular valve complete and 

 distinctly articulated. They are also all more or less 

 calcareous in the front wall, beneath the generally thick 

 epitheca with which they are covered. 



To the Microporellidce I have referred all the crustaceous 

 or f oliaceous, calcareous forms with distinct zooecial pores. I 

 cannot, however, agree with those authors who would place 

 the Adeona group in the genus Microporella for the sole 

 reason of the presence of one or more pores. The whole 

 structure is evidently different, and, especially, the ooecia 

 are not external but are modifications of ordinary zooecia. 

 The small articular processes on the avicularean mandibles 

 pointed out by Busk, although peculiar and strongly marked, 

 are not altogether confined to the Adeo7ice, but are still 

 important in this connection as they do not seem to occur in 

 the true Microporellm. I am very much inclined to the 

 view that the Adeonm should take family rank. Escharipora 

 stellata forms the transition between the two groups. In 

 the Microporellid^ I also place the species which I originally 

 described as Lepralia onagnirostris, having overlooked the 

 tubular zooecial pore, and which has been referred to the 

 genus Porina by Hincks. There has been much unnecessary 

 confusion about this genus. It was proposed by D'Orbigny 

 (" PaleontologieFran9aise," Y.432) for erect biJaminate species 

 with a special pore placed behind the mouth at the median 

 or lateral part of the cell, and he took for his types, among 

 living forms, P. Africana (D'Orb.), which he briefly defines, 

 and Eschara gracilis of Milne Edwards. Now, the pore of 

 E. gracilis, for which and its allies the generic name ought 

 clearly to be retained, is external — i.e., it is formed by the 

 overarching and junction of processes of the peristome, and 

 consequently communicates with the peristomial tube out- 

 side the true mouth. Mr. Waters has already pointed this 



