170 W. I. Robinson, 



Locality and horizon: Western New York. Devonian (Ham- 

 ilton). 

 Remarks: This species is probably a synonym for P. stylopora. 

 Pleurodicfyum zorgense Kayser. 



Fauna d. altesten Devon- Ablagerungen d. Harzes, 1878 : 229, 



PI. 33. 

 Locality and horizon: Harz Mountains, Germany, Lower 



Devonian. 

 Pleurodictyum amazonicum Katzer. 



Bol. Mus. Paraense, 1898:208; also Grundz. d. Geol. d. unt. 



Amazones, 1903 : 268. 

 Locality and horizon: Rio Maecuru, Lower Amazon region, 



Brazil. Lower Devonian. 



Genus Vaughania Garwood. 



1913 Vaughania Garwood. Quart. Jour. Geol. Soc., London, 

 Vol. LXVIII : 564. 



Original Description. — "Corallum discoid, upper surface con- 

 vex, margin lobulate; size variable, specimens occur measuring 

 up to 5 cm. in diameter. Thickness in center = 3 or 4 mm., 

 becoming somewhat less towards the margin. Base concave, 

 covered with a well-marked, wrinkled epitheca, wrinkles arranged 

 in festoon-like concentric folds parallel to the margin. Corallum 

 apparently free. Corallites very short, closely set, polygonal, as 

 a rule irregularly hexagonal ; on an average, ten corallites occur 

 in a length of 4.5 cm. Calices shallow, rather over i mm. deep, 

 walls less than 0.75 mm. thick; floors nearly smooth and flat, 

 but curving upwards at the margins to meet the base of the 

 walls. 



"In well preserved specimens the surface of the walls presents 

 a somewhat rugose appearance, resembling Nicholson's figure 

 of Cleistopora geometrica, but there are no definite ridges or 

 striae representing septa. 



"The corallum is traversed by a system of large perforations 

 or tubes, arranged on a definite plan. This is found in all well- 

 preserved specimens, though it is liable to slight variation in 

 detail. 



"Round the base of the wall of each calyx runs a polygonal 

 or roughly circular perforation or ring-canal, which follows 



