178 Rev, T. Ilincks's Contributions towards a 



recurring to the subject before ; but after ji careful reexami- 

 nation, recently made, 1 still tind myself quite unable to 

 accej)t his conclusion. Farcimia appendiculata, when deprived 

 of all its chitinous appendages and reduced, as fi\r as possible, 

 to the condition of the fossil, differs markedly from Memb. 

 articulata^ and in my judgment the differences are specific. 

 If we compare the individual zooecia we can hardly fail to be 

 struck by the points of contrast which they present and which 

 are clearly shown in Mr. Waters's figures and in my own. 

 In the first place there is a remarkable difference in the shape 

 of the cells as well as in much of their detail. That of 

 M. articulata, which is inclosed by a conspicuous raised 

 boundary line (the " band " of Waters), is elongate and hexa- 

 gonal in form. The zooecia are ranged in single file along 

 each face of the quadrilateral stem, and are quite distinct, but 

 are linked together by an extension of the marginal line given 

 off from the summit of each cell. The aperture is compara- 

 tively small, occupying the upper two thirds of the area, 

 narrow, with straight sides, rounded above and slightly incurved 

 below. A calcareous lamina surrounds the aperture, closing 

 in the space between it and the outer wall. 



In Farcimia appendiculata the zooecia are elongate-oval, 

 contracted above, so as to form a framework for the operculum, 

 the extremities in contact or nearly so, the margin ratiier 

 thin, sloping slightly outward and usually expanded at the 

 base of the cell; the aperture occupying the whole of the area 

 and closed in by a membranous covering ; the orifice semi- 

 circular, at the very top of the zooecium. There is some 

 slight diversity in the sliape of the cell, the regular oval 

 giving place in many cases to a form which narrows off 

 towards the top and expands considerably below ; but in both 

 conditions it is equally removed from that which characterizes 

 the other species. The dissimilarity of the apertures in size and 

 shape is very marked and significant, whilst the total absence 

 of the raised boundary-line which surrounds the cells and links 

 them together, and which in M. articxdata gives its distinctive 

 aspect to the colony, is strong evidence against specific identity. 

 In the presence of such important zooecial differences I am 

 fully justified in regarding the two forms under consideration 

 as distinct species. 1 may add that a more searching method 

 of investigation has only made these more apparent. 



It is difficult to compare the avicularian appendages in the 

 recent and fossil forms. Those of F. appendiculata are 

 remarkable for their size and structure, and almost fill in the 

 space between the lines of cells. Mr. Waters represents in 

 his figure two very small pointed avicularia of the ordinary 



