PLATE VII 

 TRIARTHRUS BECKI GREEN (PAGES 206-209) 



FIGURE 1. Ventral side of a large specimen ; showing, at each side 

 of the hypostoma, the antennules with their single flagellum and strong 

 basal joint ; also the biramous cephalic appendages with large gnatho- 

 bases ; the biramous thoracic limbs with gnathobases extending obliquely 

 backward in the axis of the trilobite ; and the hypostoma, metastoma, 

 and anus, in the median line. X 4. Utica Slate, Ordovician, near Rome, 

 New York. 



