140 NOTES ON THE FOSSILS OP ONTARIO- 



and are placed at intervals of from a line and a quarter to a line and 

 a half, about fourteen rows of cells occupying the space of one line 

 measured transversely. The name of C. frondosa should be restricted 

 to forms agreeing with the above measurements. On the other hand, 

 the forms with perfoi'ations varying from one line to a line and a 

 half in diameter {see Pal. H.Y., Vol. II., pi. xl., B., tig 5a) have 

 elsewhere been described by one of us, from Devonian specimens, 

 under the name of Clathropo7-a iniertexta. 



Locality and Formation. — I^iagai'a Limestone, Thorold. Kot 

 uncommon and attaining a large size. 



64. Clathropora intermedia, Nicholson and Hinde. — Polyzoary 

 forming a spreading expansion which is celluliferous on the two sides, 

 and is perforated by a series of rounded perforations which are 

 arranged in regularly diagonal lines. Perforations somewhat irregular 

 in size, oval or circular, usually from two-thirds of a line to a line in 

 diameter. Intervals between the perforations rather more than half 

 a line. Cells oblong, not so wide as long, about six or seven rows in ' 

 the space of half a line measured transversely ; so that seven or eight 

 rows of cells occupy the space between any consecutive pair of per- 

 forations. 



Clathropora intermedia (fig. 5) in some respects approaches the 



Fig. 5. — Clathropora intermedia, Nidi, and Hinde. a, Fragment of the 

 natural size ; h, Portion of the same greatly enlarged. 



genus Retepora, and is intermediate in its characters between C. 



frondosa, Hall, and G. intertexta, Nicli. The differences will be most 



clearly brought out between these nearly allied species by the 



following summary of their respective characters. 



1. Clathropora frondosa, Hall. — Perforations minute, averaging 

 one half line in diameter, placed at intervals of one and one quarter 

 to one and one half lines, about fourteen rows of cells in one line 

 measured transversely. 



2. Clathropora intermedia, IsTich. and Hinde. Perforations mode- 

 rately lai-ge, from two thirds to one line in diameter, placed at 



