Raymond & Narraway : Notes on Ordovician Triloeites 255 



6. The same pygidium, viewed from above. One third larger than natural size. 



7. The same species. Another pygidium. Same enlargement as the preceding. 



8. The same species. A cranidium, one third larger than natural size. 



9. IUcenus conradi Billings. The cephalon of a perfect specimen. Twice natural 

 size. 



10. The same species. A dorsal view of the same specimen. 



11. 12, 13. Thaleops ovata. Conrad. Three views of a nearly perfect specimen. 

 Twice natural size. 



Plate LXI. 



1, 2. IUcenus angusticollis Billings. Two views of a specimen with nine thoracic 

 segments. Enlarged four diameters. 



3, 4, 5- The same species. A specimen with eight segments. Enlarged two 

 diameters. 



6, 7. Thaleops ovata Conrad. Two views of a cephalon. Enlarged two diame- 

 ters. 



8. Thaleops arctura (Hall). The front view of a nearly complete specimen. 

 Natural size. 



9,10. Bumastus milleri (Billings). Two views of a very small specimen. Four 

 times natural size. 



Plate LXII. 

 1, 2. Bumastus billingsi Narraway and Raymond. Two views of a nearly com- 

 plete but exfoliated specimen. Natural size. 



3. Bumastus milleri (Billings). An incomplete specimen from the Lowville 

 Limestone. Twice natural size. 



4, 5. The same species. Two views of another specimen. Twice natural size. 

 6, 7. Bumastus belleiillensis Narraway and Raymond. Two views of the same 



specimen. Twice natural size. 



8. Bumastus indeterminatus (Walcott). An incomplete cephalon, showing one 

 free cheek. Natural size. 



9. The same species. A somewhat larger cranidium. Natural size. 



The specimens from which figures II, 12, 13, Plate LX, figures 3, 7, 9, 10, Plate 

 LXI, and figures 3-7, Plate LXII, were made are in the Carnegie Museum. The 

 others, with the exception of the original of figure 8, Plate LXI, are in Mr. Nar- 

 raway's collection. The original of figure 8, Plate LXI, is in the Cornell University 

 Museum. With the exception of the specimen of Thaleops arctura, all the speci- 

 mens figured were collected by Mr. Narraway. Casts of all figured specimens are 

 in the Carnegie Museum. 



