Vol. 58. ] PHYLLOCARIDA FROM PENNSYLVANIA. 449 
Puate XIX, 
Tropidocaris bicarinata, Beecher. 
Fig. 1. The dorsal side of the ultimate abdominal segment: showing the 
chevron-arrangement of the lines. Enlarged 4 diameters. 
2. The ventral side of the same. 
3. An individual with the abdomen and postabdomen in position : showing 
the carine on the carapace, the optic node, and the vascular lines 
radiating from the supposed shell-gland. Enlarged 2 diameters. 
4. The right valve of a young individual. Enlarged 4 diameters. 
5. The cephalothorax: showing the same features on the valves as the 
preceding, and, in addition, the rostrum and the median lanceolate 
plate. Enlarged 2 diameters. 
Chemung Group, Upper Devonian. Warren (Pennsylvania). 
Tropidocaris alternata, Beecher, 
Fig. 6. An entire left valve: showing the numerous alternating carine and 
posterior spiniform extensions. Enlarged 2 diameters. 
Waverly Group, Lower Carboniferous. Warren (Pennsylvania), 
Elymocaris siliqua, Beecher. 
Fig. 7. A specimen with the valves closed and the abdomen detached. En- 
larged 2 diameters. 
8. A specimen with the valves open: showing the rostrum and median 
lanceolate plate in position. Enlarged 2 diameters. 
Chemung Group, Upper Devonian. Warren (Pennsylvania). 
