270 CARBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 



mediate portion divide each septum into three nearly equal parts. Embedded in the 

 thick outer wall appear to be small secondary septa, but these do not project into 

 the central cavity. There are a few dissepimental plates develojDcd. 



It will bo recalled that Z. tnntilla has 24 septa at a diameter of 0.1 inch, })ut in 

 a larger specimen there are said to be 30. In this respect, therefore, the Colorado 

 form is fairly representative, but it may show some difference in the character of 

 the fossula and in the matter of the secondary septa. 



Locality and horizon. — San Juan region (stations 2379, 2384); Ouray limestone. 

 Crested Butte district (stations 2351, 2352, 2353, 2355, 2358); Leadville limestone. 



Zaphrentis'^ sp. a. 



I am prevented by the fragmentary character and small amount of the material 

 representing this species from identifying or giving a full description of it. The 

 shape is elongate conical and the curvature slight. It is sometimes marked by strong- 

 concentric furrows. The largest fragment seen measures over 30 mm. in diameter. 

 There are from 40 to 50 septa, which are of equal length and reach nearly, though 

 probably not quite, to the center. Their inner portions are thick, but near the periph- 

 ery the}^ suddenly become more slender. At this point also the}' are usually united 

 by sheets of massive dissepimental tissue which, appearing nearlj' simultaneously, form 

 a more or less continuous circular wall. Between this and the epitheca, which is thin 

 and delicate, the septa and dissepiments are also thin. Dissepimental tissue is fairly 

 abundant. The fossula is strongly marked, though not large. In one instance at least 

 it seems to be completely surrounded by the bent ends of the adjacent septa, and it 

 usually contains one or two of the septa within it. The effect of the structures above 

 described is to produce two zones, the inner one characterized by the massive nature 

 of its structures; the other by their delicacy. As a result, the outer zone is often 

 more or less broken away. Specimens occur in three conditions, .some being entire, 

 some retaining only the massive central portion, about which in others a more or less 

 incomplete zone of the finer tissue without its outer wall is preserved. In fact, in 

 one specimen all three states can be observed. Where only the inner zone remains 

 (a condition in which it might easily be mistaken for a complete coral), a free specimen 

 is seen to be covered with numerous saucer-shaped facets or, as it were, inverted 

 blisters. 



I can hardly think that this coral is a proper representative of Zaphrentis, but am 

 uncertain where to refer it. It has points in common with Campophyllum and is 

 possibly related to that genus. 



Locality and horizon. — San Juan region (stations 2379, 2381); Ouray limestone. 

 Crested Butte district (stations 2352, 2353); Leadville limestone. Aspen district 

 (stations 2362, 2363) ; Leadville lim^estone. 



