DESCKIPTIONS OF SPECIES. . 325 



much diminished through the thickening of the walls, uninterrupted by partitions. 

 The average diameter is 2 mm. or less, as in typical Aidopora? prossefrij the 

 shape is tubular rather than campanulate, and, indeed, the agreement in many 

 particulars is close. On the other hand, there are important differences, among 

 which may be mentioned the apparent absence from my material of tabulfe and 

 pseudosepta, and the fact that the corallum of typical Aulopora? prosseri is described 

 as prostrate and bifurcating, while in that before me the corallum is certainlj^ not 

 prostrate; for instead of having a thickness of from 3 to 7 mm., as I judge to be the 

 case in the eastern form, it is ten times that, or 6 cm., and more; nor is the growth, 

 so far as I have made out, so much bifurcating as that the corallites put forth 

 simultaneous!}' two lateral buds, each of these two others, and so on. 



In the Coal Measures of Kansas occurs a form which is probabl}' congeneric 

 with this one, although the species is different. The mode of growth is more regular 

 tlian in the Colorado form, and the general appearance is much like that of Syr/'ngo- 

 pof^a. The corallites are long, erect, and approximately parallel. The mode of 

 increase is by budding, and two offshoots ai'e as a rule developed simultaneously. 

 The corallites arc not generally connected by stolons, but occasionall}^ root-like 

 processes are put out somewhat as in Eridophylluyn,. These seem to be invariably 

 solid and are of a different character fi-om the stolonoid process which connects the 

 incipient bud with its parent. The cell walls are extensively thickened. In the 

 aperture of weathered specimens, where the wall is thinner than in the older portions, 

 there can frequently be made out a number of indistinct septa or pseudosepta. The 

 interior is otherwise entirely without structures in most cases, but in a few instances, 

 for a limited space, the cavity is intersected by numerous closely arranged, slightly 

 concave tabulte. 



It seems to me that the three forms here mentioned belong to the same generic 

 group. The mode of growth is rather different in the original Atdopora? prosseri and 

 the form last mentioned, which I have no doubt has often been identified as Syringo- 

 fora mnltuttennuntM McChesney, but the Colorado form, which may not be specific- 

 ally identical with Beede's species, is intermediate in this regard. The syringoporoid 

 colony must also have had a similar creeping growth in its earlier stages. I have 

 not observed pseudosepta or tabulas in the Colorado specimens, but the former are, 

 as a rule, to be seen only in weathered examples, while a large number of syringo- 

 poroid specimens from Kansas were examined before the tabulation was observed. 



The generic relations of all three forms is, I believe, with Mpnilipora. This is 

 particularly evident in the case of Aulopora? prosseri, though the tabulation, rare in 

 the latter, seems to be unknown in that genus. The growth of the syringoporoid 

 colonies is also unlike that of MonU'qy)ni, but may be a development of it. All 

 these species need to be thoroughly studied and revised, but it is my belief at present 



