] 54 Proceedings of the Royal Society of Victorkt. 



III. (C). — The fossils of the Dinesus ida Beds, and Notasaphus,. 

 a new genus of Trilobites. 



The need for more precise determination of the age of the' 

 Dinesus ida beds renders necessary reconsideration of the fossils- 

 found in them. Some supposed graptolites are too indefinite tO' 

 be of use. The trilobites give the most important evidence. 

 They were discovered by Mr. Ferguson, and some specimens 

 were collected by Mr. Lid gey. The specimens consist of some 

 cranidia and pygidia scattered together in an iron-stained shale. 

 Mr. R. Etheridge, jun., who described the specimens, naturally 

 concluded that they belonged to the same species. Mr. Ethe- 

 ridge gave a detailed description of the material then available ;. 

 he referred it to a new genus and species, Dinesus ida. He did 

 not refer the genus to a family, though he carefully contrasted it 

 with several lower cambrian genera. 



In order to obtain more material to settle the generic affinities 

 of Dinesus, Mr. Ferguson made an excavation in the shales 

 during last June, and obtained additional specimens of the trilo- 

 bites. The new specimens are also fragmentary, but their 

 evidence shows that at least two distinct trilobites have been 

 included in Dinesus ida. They show that the pygidia and' 

 cranidia figured as Dinesus do not belong to the same genus. 

 The pygidia figured by Mr. Etheridge agree better with some 

 cranidia recently obtained by Mr. Ferguson. One specimen of 

 Dinesus shows two of the thoracic segments. 



Mr. Ferguson's recent collection enables me to suggest the 

 following arrangement of the trilobite remains from this horizon. 



1. Family Asaphidae. 

 Genus Dinesus, R. Etheridge, fil., 1896. 



Diagnosis. — An asaphid with a nearly smooth glabellum, whicb 

 has the sides sub-pai-allel or slightly contracted in front ; the 

 axial grooves are deep. The third side-lobes are cut off from the^ 

 rest of the glabellum by the junction of the third side furrows 

 and the neck furrow. Eye lobes small, and slightly projecting. 

 Facial suture cutting the frontal border in front of the axiali 



