DESCEIPTIONS OF SPECIES. 327 



these objects could be demonstrated, their evidence might be of value in its bearing 

 upon the disputed point as to whether Avlopora really does belong, as has been 

 claimed, to the Alcyonarian corals. At least the evidence would be in force to the 

 extent that these forms are related to AulojMra. 



Another specimen from the Crested JButte region (station 3303) which probably 

 belongs to the same species, though consisting of but a few corallites, yet seems to 

 shed light upon the means hj which extensive coralla are built up by these more 

 or less disconnected tubes. In this specimen, in which the growth is more clearly 

 shown through combined silicification and weathering than in th'e others, some of 

 the corallites are closely proximate and, where in contact, develop strong concentric 

 rugae, which alternate in the two individuals adjacent to one another, and so in 

 a measure interlock. These projections appear to be somewhat radiciform, and 

 to a certain extent resemble the structures which form a distinguishing character 

 of the genus £ridoj>liyllum. 



In this specimen, as in those previously described, the corallites have a diameter 

 of about 2 mm. ; the walls are thickened, and tabulaj and septa appear to be absent. 



Locality and liorizon. — San Juan region (station 2199); Hermosa formation. 

 Crested Butte district (stations 2290, 2303) ; Maroon conglomerate. 



LEPTOPORA Winchell, 1863. 

 Leptopoea winchelli White. 



1879. Leptopora winchelli. White, U. S. Geol. Geog. Surv. Terr., Bull., vol. 5, p. 211. 

 Carboniferous: Near the forks of Logan River, in Bear River Range, northern Utah. 



1880. Leptopora intichelli. White, U. S. Geol. Geog. Surv. Terr., Twelfth Ann. Rept., for 1878, pt. 1, 



p. 121, pi. 34, fig. llo. 

 Carboniferous: Near the forks of Logan River, in Bear River Range, northern LTtah. 



If the single specimen obtained were in a more perfect condition it is possible 

 that it would pi'ove distinct from the species described bj^ White. It has a some- 

 what irregular semicircular shape, with a diameter of about 45 mm., and seems to 

 have been attached to a large specimen of Platyceras nebrasJcense. The constituent 

 cells vary greatly in size. Some of the larger ones have a diameter of almost 5 mm., 

 rather larger than anything in the material described by White. The height of the 

 corallum seems to be insignificant compared with its lateral expansion, but some of 

 the corallites must have had a length of at least 5 mm. There appear to have been 

 no tabulae, and no septa have been observed on the thin cell walls. 



Locality and horizon. — San Juan region (station 2279); lower portion of Her- 

 mosa formation. 



