T. H. Clark — New Trilobite Appendage. 245 



Art. XXIV. — A New Trilobite Appendage; by Thomas 



H. Clark. 



Among all of the faunal assemblages in the Levis 

 formation the most interesting and the richest in hitherto 

 unrecognized fossils is the so-called Shumardia limestone. 

 Billings referred to this as ''thin-bedded limestone inter- 

 stratified in the graptolitic slates" (Pal. Foss. Can. 1865, 

 p. 93) in recording the locality of the single new fossil 

 which he described from it. That only one species should 

 have been known at that time is very remarkable, for in 

 places it is crowded with fossils of all descriptions. To 

 be sure, the limestone is difficult of access in place, and it 

 may be that Billings was not content with fallen blocks 

 at the base of the cliff. T. C. Weston, lithologist for the* 

 Canadian Geological Survey, later made large collections 

 from this horizon, which he named the Shumardia lime- 

 stone on the labels which he affixed to his specimens. Dr. 

 Raymond recognized the name in his paper on the succes- 

 sion of the faunas at Levis, and listed under his Zone D, 

 the fauna then known to characterize that bed. Eecently 

 the writer has made a large collection of this horizon 

 which includes all of the previously recognized species, 

 and a great many new ones. An incomplete summary 

 of the fauna, which is not yet thoroughly worked over, is 

 as follows : — 



Plants Obscure algse. 



G-raptolites 19 species. 



Brachiopods 



Inarticulate 11 species. 



Articulate 2 species. 



Crustacea 



Trilobites 10 species. 



Ostracods Numerous. 



Cirripedea 2 species. 



Annelids (?) 



Conodonts 4 species. 



Serpulites 1 species. 



With the exception of a few small articulate brachiopod 

 shells, all of the specimens of the species listed above are 

 now composed of black carbonaceous material, which indi- 

 cates that their original shell or skeleton was of chitin or 



