0?i the Monticidipojoids of the Cincinnati Grojip. 177 



4. XVI II., p. 86, 1876. {non Diamdites rhombiciis, Dybowski, Die 

 Chastetiden, 33, 1877). 



Alonotrypella quad rata, Ulrich. Jour. Cin. S. Nat. Hist., V., 

 248, 1882. 



Monotrypella sub-quadrata, Ulrich. Ibid, V., 249, 1882. 



Corallum dendroid, occasionally sub-massive, branches cylind- 

 rical, varying from two to five lines in diameter, often ending in 

 bulbous extremities. Surface smooth or nearly so. Corallites 

 thin-walled below, slightly thickened toward the mouths, all 

 similar. Calices generally in parts, obliquely rhomboidal, some- 

 times polygonal, arranged in regular diagonal rows, the direction 

 changing at short intervals. Lips very thin. Very few or no in- 

 terstitial tubes, 



Obs. This species is easily distinguished by the peculiar 

 rhombic form of the calices, arranged in regular curved, diagonal 

 lines, crossing each other obliquely. If the cells on the surface ap- 

 pear polygonal, the weathered ends of the branches invariably 

 show the rhomboid form of the calices. The form described as 

 sub-quadrata, Ulrich, is stated to have a few interstitial cells, but in 

 all other respects it is precisely like qiiadrata. One of us has a 

 specimen showing quite a number of interstitial cells placed in 

 rows on one part, while the other portion shows none of these 

 small cells. Clusters of slightly larger cells forming maculce are 

 occasionally present. 



Formation and Location : Lower Silurian, Upper beds of 

 Cincinnati Group. Different localities in Warren and Clinton 

 Counties, O. 



23. M. VARiANS, U. P. James. The Palaeontol., 36, 1881. 



Chatetcs varians, U. P. James, The Pal?eont., 2, 1878. 



Corallum variable in form, ramose, incrusting or massive. In 

 the ramose forms branches irregular, rounded or sub-cylindrical, 

 digitate; the massive forms irregular, contorted, flattened or lobate, 

 four or five inches in diameter, throwing out shoots in various 

 directions ; frondose and celluliferous on both sides. Surface 

 smooth. Calices sub circular, oval or polygonal; walls thick; in- 

 terstitial cells few to numerous. (Plate 2, figs. 4^7, /;.) 



Obs. This is an extremely variably species as far as its mode 

 of growth is concerned. The incrusting forms seem to be the 

 young corallums. It has been compared to M. jamesi, but it 

 differs in not branching regularly, in having thinner walls and 

 more regular calices. 



