66 
GROUP OF SPECIES WITH 23-33 AXIAL JOINTS IN PYGIDIUM. 
Encrinurus punctatus.. ........ (Hattie. 3-30 axial joints, 9 pleurae 
elockest, MoCoy ..........; (Entire) oi. 28 Hy he = 
—Trentonensis, Wale... (tail)... 4 2 . 9 a 
Barrandet, DekKon ........ | ee & tail) 25-26 “ i 9 a 
multi-segmentatus, Portl (tail) ........... 32 4 Zz g-Io ‘ 
Stats, AO Lunia (tail).....not known ‘' ean, uu ‘ 
——tuburculosus, Collie........ (a) ea 25 m “ 8 i 
—-odeltoides, Slinin....,..... (UAT) betes os 24 . : 7 » 
GROUP OF SPECIES WITH 20 AXIAL JOINTS IN PYGIDIUM. 
Encrinurus sexcostatus, Salter a oe 20 axial joints, 6 pleurae. 
——-Aniericants, Vood,. ...., (CBO age fo] at - 5-6 
——odrnatus, H. W....(tail, Ohio specimen) ...20 “ - 7-8 
GROUP OF SPECIES WITH 16-18 JOINTS TO PYGIDIUM. 
Encrinurus nereus, Hall..,..... (tail).............18 axial joints, 8-9 pleurae. 
beatiie Milley. in. (Ee) as. 18 o te, a 
—Threcheri, Foerste.......... CURE Rae acs 18-20 “ uf 7—8 ie 
PATiCOstatud; Wale... (tell)... 16 : ie 6 a 
ranmilis, Clarice... 2, (CHOC \en 14-16 “ ue 6 ue 
LBV IS, AUS sili (Ete) crs 14 . e 8 fn 4 
schisticola, Tornq......... (UIE) eo 14-16 ‘ i | eee 
Bowningi, Foerste......... CH MIGS ace 18 = Le cia, a 
Encrinurus vigilans, Hall ..... (Entire)........18 axial joints, 9 pleurae. 
GROUP OF SPECIES WITH O-I5 AXIAL JOINTS IN PYGIDIUM, 
Encrinurus variolaris, Brong. (Entire)........ 9-10 axial joints, 7 pleurae., 
expansus, Hlaswell........, (QSpooht 14 e 28 ul 
ta Ase NCCU ied iva: (Gopher Leetd. | Pe sabe ol! 
ODiISHE, ANG cece: (Gch ees oe ey 12 oe 16 “ 
——Indianensis, Collie ...(head and tail)...15 - Zaveaile, ve 
The species may be grouped as follows: 
H.NCRINURUS. 
ncrinurus punctatus, Stockesi, ‘I'rentonensis, Barrandei, 
. . vigilans, Seebachi. 
3. EH. sexcostatus, deltoides. 
4. HK. multi-segmentatus, striatus. 
5. H, Nereus, ornatus, Egani, Threcheri, Americanus. 
6. I, raricostatus, vannulus,. 
CRYPTONYMUS. 
7. HE. variolaris, expansus, obtusus, levis, 
8. Bowningi. 
