NORTH AMERICAN GRAPTOLITES 305 
If now the Dicel/ograpsus zones cannot be pre-Trenton, and must be sub-Utican, 
by exclusion they only can only be Trenton, and as a rough approximation we may 
say lower and middle Trenton respectively. Following them, of course, are the Utica 
and Lorraine horizons. 
3 Contrary to the opinion formerly expressed as the result of insufficient study, 
the Arkansas beds belong rather to the Lower than to the Upper Dicellograpsus zone. 
To show this, the following table is given showing the range of the species as ascer- 
tained in New York and Canada : 
o o 
§ 6 
N N EI 
2 2 2 
na oa $ 5 
ARKANSAS SPECIES = eee = 
lo u i ist 
on ? = 5 
=| £ = 
oO Oo D 
Be ay 
(a) a 
Didymograpsus SAMUNCAWINS  soooasasess oo caus 
serratulus.. gh 
Stephanostaptusmeracilishess-m cit srs acesnaa or x 
Leptograptus (like annectans)................ 
Dicellograpsus rigidus...........-......0 005. Gl 
GivaniCatuSec ees cde eae < 
oo intortus x< 
Berceiceciare karen nearest sedate q 
we CLEC AMS Ie: eeaaray ce aseteen oid a) oe eeu neat Var. LH UH 
Dicranograptus TAMOSUS....-. 2-2. eee eee SK xK SK 
i MIGHOlSOMMe sss rake ae eee sere ave eels x< 
ue o parvangulus.......... 
s Ss arkansasensis........ | x 
Climacograptus CUOMO @ acm Some cep peal aD x Var. 
DICORMIGAPE ra eine ek reste y« x< SK 
Diplograpsistoliaceis. aces. eisee oss ese eee xX aX >< s< 
s WHMCS coAns tract chemo pre cRea te 
* vidal REN Cheeses @ cecan Echo g Glokicrnncereee x 
= AMEPAIUONUS 655 caco ad bonod oe enon x 
Cry ptoprap tusrinicommissse ewes Giclee ee yee x x 
Masiopraplus mucronatus eserves ae ele >< x 
(SIOSSO GT APSUSIGI ia tsa er eter eee ie) ar x | 
Dictyonema obovatum........ bis Cate eeRt ae a cnn 
Dendrosnap isis praca e eee cree ease so 
iamnosraptusiibarrandien sewers en ee ree DG x< 
The following abbreviations mean: Gl. Glenkiln; LH. Lower Hartfell; UH. 
Upper Hartfell. Phe species so marked are known in America only in Arkansas, 
and the comparison is with their ascertained foreign range in strata equivalent to 
those represented in the column. 
™ Zone first noted by Lapworth (Trans. Roy. Soc. Can. for 1886, V., Sec. IV., p. 
172), as “Zone without Coensgraptus gracilis.’ The collections referred here were 
from the Coye Fields, from St. John Market, Quebec, and from the north side of the 
Island of Orleans. Subsequently Ami (Ann. Rep. Geol. Surv. Can. for 1887, p. 46K), 
found Stephanograptus (“ Coenograptus;” species not stated) in this zone. 
