LOWER CARBONIFEROUS FOSSILS. 509 



This species is interesting as being the first representative of the genus 

 Aulopora described from the Carboniferous rocks of this country. The 

 form in question presents some apparent divergences from typical Aulopora 

 habit and structure, such as, if they could be established, would be suffi- 

 cient for generic differentiation. However, I have but one specimen of the 

 species, and it does not afford conclusive evidence on the points in question. 

 The corallum appears to have been free, or at all events to have outrun the 

 surface on which it was creeping, and the unannexed portion to have been 

 broken away; for there is no evidence of attachment in its present condition. 

 The corallites are small and cut up internally by irifundibuliform dissepimental 

 tissue, somewhat as in Syringopora. At least, there are usually to be seen 

 one or more cylindrical walls internally concentric with the theca. It may 

 be thought, and perhaps correctly, that this is the initium of a Syringoporoid 

 colony. As against this view, it may be stated that no such colonies are 

 known from the locality in question, nor would the hypothetical colony 

 restored from this initium probably agree specifically with any yet 

 discovered in the Yellowstone Park. 



Formation and locality: Madison limestone, Bighorn Pass, Gallatin 

 Range, cherty belt; Arnold Hague. 



SYRINGOPORA Goldfuss, 1826. 



Syringopora aculeata n. sp. 



PL LXVII, figs. 5a, 56. 



Corallum large, never favositiform ; corallites small, radiating, sepa- 

 rated by distances varying from one-half to five or six times the diameter 

 of the average corallite. Usually about 1 diameter apart. 



Corallites about 1.5 mm. in diameter. Septa represented by spines 

 set in about twenty-five vertical rows. The number appears to be varia- 

 ble, and can not be stated with exactness. The spines are long and very 

 numerous, so that they form a striking feature in any transverse or longitudi- 

 nal section. Dissepimental structures well developed, spinose, vesiculose 

 infundibuliform, the dissepimental plates converging very gradually. 



Formation and locality: Madison limestone, White Mountain, Absaroka 

 Range; Arnold Hague. Crowfoot Ridge, Gallatin Range, bed 29; J. P. 

 Iddings and W. H. Weed. 



