152 



NEW YORK STATE MUSEUM 



Inocaulis arbuscula Ulrich. Ibid. 



Calyptograptus ? arbusculus Spencer. Acad. Sci. St Louis Trans, v. 4 (bull.) 



1884. p.563 

 Dictyonema arbusculum Gurley. In J. F. James, Cin. Soc. Nat. Hist. Jour. 



1892. p.153 

 Inocaulis arbuscula Gurley. Jour. Geol. 1896. 4:300 

 Dictyonema arbusculum Nickles. Cin. Soc. Nat. Hist. Jour. 1902. 20:72 



Description. Rhabdosome small (15+ mm), flabellate or infundibuli- 

 form, rapidly expanding by successive bifurcations, the branches diverging 



from 6o° -70 , narrow (.3 mm), gently 

 undulating or curvilinear in direction 

 in the proximal portion, forming long 

 oval meshes, principally by contact, but 

 becoming straighter more distally and 

 then probably forming dissepiments. 

 Thecae projecting, forming distinct den' 

 tides, numbering about 13 in 10 mm. 

 Sicula not observed. 



Position and locality. Ulrich records 

 it from the Middle third of the Eden 

 shale at Covington, Ky. and Nickles in 

 his " Geology of Cincinnati " \loc. cit. , 

 lists it as a fossil of the middle Utica or 

 Batostoma jamesi beds. 



Remarks. This species has been 

 twice described, first by Ulrich [1879], 

 who noted the presence of the denticles, 

 and then by Gurley [ 1892], who recorded 

 the curvilinear direction ol the; branches 

 and the presence of dissepiments. We figure here an enlargement of a 

 well preserved specimen (metatype) of the Ulrich collection from which we 

 have obtained the above given diagnosis. The specimens give the impres- 

 sion of being but the proximal portions of larger rhabdosomes for they 



Fig. 57, 58 Dictyonema arbuscula O'J'fid 1 ^ 

 Fig. 57 Copies of original drawings. Fig. 58 F.n 

 largement (x 5) of authentic specimen. Original in 

 Ulrich collection 



