Beecher — Ohservations on the Genus Rojuingey^ia. 9 



but two corallites. In Pleurodictyiom lenticular e as in Aulo- 

 jpora no tabulae are present, and the only structures within the 

 tubes are rows of trabeculse. It was also shown ^' ^ that the 

 pores in the Favositiclge may be likened to aborted buds which 

 attained no further development than the formation of a pore. 

 The corallites in Aulopora generally give off one or two buds and 

 then soon reach their limit of growth, while in Romingeria 

 the corallites may grow to indefinite lengths and repeatedly 

 send off whorls of buds. 



It is well known that many species of Favosites develop 

 faint septal longitudinal ridges or rows of spines. Typically 

 these number twelve, thus agreeing with the characteristic 

 number of buds and septa in R. unihellifera. The corre- 

 spondence in the number of septa and mesenteries indicates 

 that from each interseptal space buds may arise, so that 

 Favosites has twelve proliferation potentialities at each com- 

 plete cycle of budding. 



Girty ^ has fully discussed these features in Favosites^ and 

 has shown that what should be considered as the archetypal 

 form consists of an initial corallite with six primary radially 

 arranged buds. Six interstitial cells constitute the next gen- 

 eration, and complete the cycle of twelve radii of gemmation. 



These points of similarity in the budding habit of Favosites 

 and Romingeria^ together with the identity of most of their 

 internal structures, clearly indicate their genetic affinities and 

 point to their common origin. 



Paleontological Laboratory, Yale University Museum, June 6, 1903. 



References. 



1. Bplings, E. — On the Fossil Corals of the Devonian Eocks of Canada 



West. Canadian Journal, new series, vol. iv, 1859. 



2. Eominger, C. — Fossil Corals. Geological Survey of Michigan, Lower 



Peninsula, 1873-1876, vol. iii, pt. ii, 1876. 



3. Nicholson, H. A. — On the Structure and Affinities of the "Tabulate 



Corals" of the Palaeozoic Period, 1879. 



4. Davis, W. J.— Kentucky Fossil Corals, pt. ii (1885), 1887. 



5. Beecher, C. E. — The Development of a Paleozoic Poriferous Coral. 



Transactions of the Connecticut Academy, vol. viii, 1891. 



6. , — . — Symmetrical Cell Development in the Favositidee. Ibid., 



vol. viii, 1891. 



7. Girty, G. H. — Development of the Corallum in Favosites forbesi var. 



occidentalis. American Geologist, vol. xv, 1895. 



8. Lambe, L. M. — A Ee vision of the Genera and Species of Canadian 



Palaeozoic Corals. Contributions to Canadian Palaeontology, 

 vol. iv, pt. i, 1899. 



