216 
Geological 
Stage 
REPORT— 1883. 
Synopsis of the Genera of the Fossil Phyllopods. 
Genera 
De 
Raibl beds 
(Trias, 
Hallstadt) 
Devonian . 
Devonian . 
|Devonian . 
Devonian . 
Devonian , 
| 
| 
Silurian 
| 
hniowide Silu- 
| rian and 
Devonian. 
Carbonif. 
& Deyon. 
2510) 
— a. 
Carboni- 
ferous 
Silurian 
Lower Silu- 
rian. F 
Lower Silu- 
rian. 
Silurian 
I. Carapace UNIVALVE. 
(1.) FLAT SHIELD. 
1, Neither sutured nor ridged along the back. 
(A.) Posterior border entire. (Entire behind.) 
Silurian facet H.W., 1866 
Aspidocaris, Reuss., 1867 
Spathocaris, Clarke, 1882 
Pholadocaris, H.W., 1882 
Lisgocaris, Clarke, 1882 
Lllipsocaris, H. W., 1882 
(B.) Posterior border slightly notched. 
Cardivcaris, H. W., 1882 
(C.) Posterior border deeply notched. 
? Pterocaris, Barrande, 1872 
Dipterocaris, Clarke, 1883 . 
2. Ridged along the back. 
Dithyrocaris, Scouler, 1843, 
(Argas, Scouler, 1835). 
Rachura, Scudder, 1878 
3. Sutured along the back. 
. Aptychopsis, Barr. (& H. W.), | Angular notch 
1872. 
A 
B. Peltocaris, Salter, 1863 . 
C. Pinnocaris, R. E. Jr., 1878 
D 
. ? Crescentilla, Barr., 1872 
Slight notch:  striz 
concentric far back. 
Notched before and 
behind 
No. of 
No. of | caudal 
exposed] SP1nes 
Special character ae Styles 
aie blots 
sty 
ments nrahe 
telson 
Angular notch* 4? 3? 
Angular notch* 
* Round shield. 
Angular notch t 
Sinuous notch t 
Oblong notch ft 
Rounded notch t 
+ These shields 
differ in shape. 
. | Front notch oblong 
(Open behind.) 
. | Both notches angular 
(test radiately 
marked) 
. | Bothnotches angular 
(Like Apus.) 
Ridged and some- 
times prickled 1, 4, 
or6. 3 
(Telson only known) | — 3 
Rounded notch . 4? 4? 
adn pb 
