from the Upper Devonian Rocks of Ohio. 35 
elliptical or elongate-ovate in form, with a straight dorsal mar- 
gin; surface aaa striate, no nodes or ridges. Lingu- 
locaris Salter, 1 
4th section: Carapace triangular, dorsal margin straight; sur- 
face punctate or reticulate, and concentrically striated (growth 
or pastalose. ichinoc arts, new gen. 
6th s penteot biel oval or ovate; no straight 
etal ie sonpeneee no hinge; anterior end rostrated or 
pease surface destitute of nodes or ‘ridges. Physocaris Salter, 
860. 
7th section: Carapace composed of three pieces, or apparently 
of three, two of which are semi-circular, with the anterior end 
of each obliquely i sang forming, when the two are u nited, 
an anterior triangular notch into which the third or sais 
pers. is inserted ; ama se concentrically marked by growth 
ines; no nodes orridges. Peltocaris Salter, 1866; Discinocaris 
Woodwar d, 1866; Aptichopsis Barrande, 1872; Prerocaris Bar- 
rande, 1872 (not Heller, 1862). 
It will be readily seen, from the above nbyeies that Echino- 
carts differs materially in the features of the carapace from all 
the other genera enumerated. The features of the abdomen 
and caudal parts are not as reliable as those of the carapace, 
ut are somewhat distinctive, as arg be seen by the following 
table of comparison. mark of interrogation indicates that 
the parts are unknown or only caeially known n.) 
nus. Abdominal segments, Caudal spines 
Ce ris 5 or 6 smooth 3 
DCN POOMPIE (he 1 smooth 3 
ymenocaris 8 smooth 6 
Dictyocaris 6 smoo 37 
hysocaris 5 
Echinocaris 4 spiney 3 
Discinocaris 4? aT 
Peltocaris 3 smooth 3 
Caryoustis wie cs dae 2 oC 1? 3 
SOOORIE oo an eed eck cone ? ? 
Ha fs ere mae 4 g 
? ? 
paces bi, wad ot et ? 
Possess in one species Fouitteai segments in the bdadiee; aly 
six of which are naked 
