THE 
AMERICAN GEOLOGIST. 
Vol. XV. 
MARCH, 1895. 
No. 8. 
DEVELOPMENT OF THE CORALLUM IN FAVO- 
SITES FORBESI. VAR. OCCIDENTALIS. 
By GEDKtiK H. GiKTV. New Haven, Ct. 
One American I'epresentiitive of Fdrosites forhcsi from the 
Wenlock limestone of England is the variety occ/V/e///''//.v. Tlie 
type specimen described b}^ Prof. Hall in lS71),f as well as the 
material on which the present paper is based, were found in 
the Niagara shales of Waldron. Indiana. 
The varietal tlitferences in these two forms are considerable. 
In the American sijecies the corallum is small, usually not 
over 6 cm. in diameter, and the shape pyriforni or hemispher- 
ical, thus differing slightly from V.forhcsi. The indivitlual 
cells, moreover, vary from 1 to ;5 mm. in iliameter,f while, in 
the English variet}', they range fr(un o to '1 \\\\\\.\ In the 
original description of F . forhtai, Edwards and Haimc dit not 
mention the character of the mural pores, ja't the figures in- 
dicate that these are small and closely set, with ten oi- twelve 
rows to a corallite. In the variet}^ ocvideiif.dlix^ however, they 
are of large size and widely separated, both laterally and lon- 
gitudinally. It is rare to find more than one row between any 
two corallites, and occasional!}' none appear to be present. The 
strongl}^ pustulose character of tlie cell walls seen in British 
specimens has not been observed in American forms.§ 
*Ackn()wlt'(l<i-emenls are due Dr. (". K. Hci-cliiT Torllic use (if material, 
as well as fur valuable su^-g'eslidns in Ihi; |)rei)arali()M of tiiis paper, 
fllall. 1S7!). (iedlouy of IiHliaiia. II Annual Report, p. -l-l'.K 
^Edwards and Hainie, DS.lO-:)^. Hritisli Fossil (.'orals, p. •.'.")!». 
SHall. isrit. (ieojoiivof Indiana. II Animal Ueporl, p. •i:!0. 
