56 BRYOZOAN FAUNA OF THE ROCHESTER SHALE. 
Genus CLATHROPORA Hall. 
Like Ptilodictya save that the zoarium consists of branches anastomosing so as to form a 
regular network with round or oval fenestrates. 
Olathropora frondosa Hall. 
PI. XX, figs. 5-11; PI. XXI, figs. 6, 7. 
(In l hropora frondosa Hall, Nat. Hist. New York, Pal. II, 1852, p. 160, pi. 40B, figs. 5 a-c. 
Clathropora frondosa Grabaii, Bull. New York State Mus. No. 45, 1901, p. 174, fig. 75. 
Zoarium large, frondescenl , consisting of anastomosing branches forming a network which 
in old examples is often 10 cm. or more in length and width. Proximal portion marked 
with finer longitudinal stria 3 , long and pointed in young examples, but with age becoming so 
thickened as to he wedge shaped. This par! of the zoarium articulates into a cup-shaped 
depression of a spreading base attached to foreign objects. The older the zoarium flic more 
thickened is the proximal portion, and here the brandies sometimes become so broad hat 
the fenestrates are obliterated. Branches elliptical in cross section 1 .5 to 3 nun. in breadth 
and carrying on each side from S to 15 or even more ranges of zocecia arranged in linear 
series. Fenestrates oval, 1 .2 by 2 mm. being an average dimension although, because of age 
and position, considerable variation is found: about 2.5 or 3 in 10 mm., measuring longi- 
tudinally, and the same number in 8 or mm. diagonally. Zooecial apertures rhomboidal, 
oblong-quadrangular, or elongate-hexagonal, the shape varying in different portions of the 
zoarium, 8 to 9 in 2 nun. longitudinally and 1 1 in the same space measured transversely. 
There is no associated species save the variety mentioned below with which this might 
be confounded. A large complete example with its network of branches, oval fenestrules 
and pointed base forms an exceedingly handsome cabinei specimen. 
Occurrence. ■*■ Fragments are common, but complete specimens are more rarely found. 
Lock port , N. V., Thorold, Hamilton, and Grimsby, Ontario. 
Catalogue numbers, 441 lb, I 11 17. l\ S. National Museum. 
Clathropora frondosa entermedia Nicholson and Hinde. 
Clathropora intermedia Nicholson and Hinde, Canadian Journal, new ser., XIV, L874, p. L40, tig. 5. 
Clathropora intermedia Nicholson, Pal. Province Ontario, I s7.5 . p. 59, flg.29a, b. 
Original description.— Clathropora intt rm edia Nidi, and Hinde. Perforations moderately largo, 
from two-thirds to one line in di;imetcr, placed a1 intervals of rather more than half a line, six or seven 
rows of cells in half line, and se\ en or eight rows between any two perforations. 
Niagara limestone. Thorold, Ontario. 
The authors of this form distinguished it from Clathropora frondosa mainly on account of 
the possession of larger fenestrules. As shown under (he above description, (he size of the 
fenestrules is a variable character. The only additional character found by the writer to 
distinguish the two forms is thai the zocecia of C. intermedia are slightly larger than those 
of Hall's species; the former having 7 in 2 nun. longitudinally, and 9 to 10 in the same 
space transversely, while the latter, as stated above, has 8 and 11 in the corresponding 
measurements. The two distinctive characters mentioned are so slight that C. Intermedia 
can hardly be regarded as more than a variety of C. frondosa. 
Occurrence. — Rochester shale, Thorold and Hamilton, Ontario. 
Catalogue numbers, 35749, 35750, U. S. National Museum. 
Clathropora alcicornjs Hall. 
PI. XX, figs. 1-4. 
Clathropora alcicomis Hall, Nat. Hist. New York, Pal. II, 1852, p. 150, pi. 1015, tigs. 4 a-c. 
Clathropora alcicomis Grabau, Hull. New York State Mus., No. 45, idol, p. 174, fig. 7(i. 
This form is easily recognized from the figures given by Hall and is distinguished from all 
other species of the genus by the failure of the branches to form a network with oval fenes- 
trules as in the typical species. Otherwise the structure is as required for the genus, as the 
