ART. 21 ORDOVICIAN TRILOBITES — ULRICH 21 



cheeks and the fact that the edge of the outer band, which should 

 correspond to the palpebral band, departs fartherest from the dorsal 

 furrow at the posterior lateral angles of the cranidium instead of in 

 front. The anterior extension of the middle part of the head also is 

 difficult to understand as a normal modification of the generic type. 

 To say the least we require more information concerning this trilobite 

 before it can be accepted as a properly classified and unquestionable 

 species of Telejyhus. 



6^«'«rr<?wce.— Balclatchie group, Balclatchie, Girvan District, 

 Scotland, 



TELEPHUS AMERICANUS Billings 



Plate 2, Figures 22-27 



Telephus americanus Billings, 1865, Pal. Foss. 1, Geol. Survey Canada, p. 



291, fig. 281. 

 Telephus americanus Hadding, 1913, Slaktet Telephus Barr., Geol. Foren. 

 Forhancll., vol. 35, Haft 1, p. 4, text fig. la, 6. 



Original descnption. — 



Glabella obtusely conical, length one-sixth greater than the width, rather 

 strongly convex ; front uniformly rounded ; sides parallel ; neck segment and fur- 

 row forming nearly one-third of the whole length ; the furrow narrow and ex- 

 tending all across. The fixed cheeks are crescentiform, rounded on the outside, 

 terminating posteriorly at the front edg3 of the neck furrow and extending 

 around one-third of the width of the front of the glabella ; an obscure groove 

 just outside of the middle of the cheek, parallel with the margin in the front 

 half, but i-unniug out to the edge before reaching the posterior corner. In 

 front of the glabella there are two small projecting points. The surface is 

 obscurely tubercular, and there is a small tubercle on the middle of the neck 

 segment. 



Length from two to three lines. 



The detached glabellte occur in considerable numbers, but I have seen none 

 of the other parts in connection with any of them. There are no fragments 

 that can be identified as belonging to this trilobite, except the glabella. 



Through the kindness of Dr. E. M. Kindle, of the Geological Sur- 

 vey of Canada, I was given the opportunity of studying five cranidia 

 used by Billings in describing this species. These were photo- 

 graphed, and plaster casts made of them are now in the United 

 States National Museum. Three of the cranidia doubtless are strictly 

 conspecific, the fourth also may be but requires more preparation 

 before it will be fit for final classification. The fifth, which has a 

 longer glabella, with straighter sides, a pair of faintly impressed pits, 

 and smoother surface, may belong to a distinguishable variety or 

 species. As these specimens show slight differences I propose that 

 the one which bears the number T00& be selected as the holotype of 

 the species. It is the best of the lot and most probably is the one 

 figured by Billings and also the one of which the plaster cast was 



