ART. 21 ORDOVICIAN TEILOBITES ULEICH S 



the cheeks and eyes, so that it was only after satisfying myself 

 regarding the free cheeks that belonged to each of the associated 

 trilobites that the few unassigned remaining cheeks began to be 

 considered as probably belonging to Telephus. It was in the occa- 

 sional brief periods of 1908 to 1913 that could be devoted to the study 

 of the Appalachian Ordovician faunas that I worked out the char- 

 acters and wrote most of the following descriptions of the American 

 species of the genus. Then before my paper could be completed and 

 published Hadding's work on the genus appeared. Though his paper 

 interfered with my slowly maturing plans and delayed publication 

 of my results I am not sorry because so far as it went I know that 

 Hadding's paper was a better contribution to the subject than mine 

 at that time would have been. On the contrary, I was pleased to 

 note that in all essential respects our conclusions were in accord. 

 As regards structural features I diifered then and differ now from 

 his view of the two downwardly directed anterior spines, which he 

 claims " are only parts of the cephalic limb intersected by the facial 

 sutures." Possibly this is true of the European species studied by 

 him, and on first sight it appears so also in the American species. 

 However, on closer investigation I found that in all of the latter 

 these are actually hollow spines with subcircular cross-section and 

 separated at their bases by a depression or cleft from a much shorter 

 prominence or angle of the rim against which the inner end of the 

 free cheek abuts. This condition is clearly shown not only by a 

 hundred or more of my specimens but equally well also in the types 

 of T. amiericanus Billings. Text figures reproduced from drawings 

 of a plaster cast of the best of the latter are given in Hadding's 

 paper, but regarding these I can say only that the draughtsman for 

 some unknown reason overlooked the separateness of the spines which 

 is clearly indicated on at least the right side of the specimen (see 

 pi. 2, fig. 23). Under the circumstances I am persuaded that the 

 apparent difference between the American and European species rests 

 on imperfect observation. 



REVISED DESCRIPTION OF GENUS TELEPHUS 



With the data now in hand the following amended definition of 

 the genus is presented. 



Family TELEPHIDAE Angelin 



Genus TELEPHUS Barrande 



Small, strongly convex and probably slender opisthoparian trilo- 

 bites, with narrow pleural parts well separated from the relatively 

 wide axis ; carapace known only from dismembered parts. Cephalon 



