4 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
Diagnostic table of some cranial and dental characters of North American MuniD&. 
MURIDZ. 
MURINE. ARVICOLINE. 
Mures. Sign.odontes. 
Tepe || Arvicola. 
AEs e = a ze & 
JSlS/ElE/ STE lel 8) Slelelelal . 
- |(S/Slsl/si sisi als] Bl sls eisiela 
g S/SlS/Sl(E/EIEIS/3|2 2 / B/E) 2/2 
HS 4 alélelélé6élalolalslalaialola 
Denta) formula: 
rit oot, pee =e | + Playtest iets isles lays 
Anteorbital foramen : 
A large slit-like canal in the maxillary, with 
pyriform orifice, bounded exteriorly by a 
plato\otW NOG ness ee eee eae ene + [+/+] +]+] 4/4] +/+] 4+) 4]/4+]4+ 
Top border of this foramen deeply nicking the 
root of the zygoma, viewed from above..-..--. + +/+) +)+] 4/4] --]--] --]--]--]-- 
Root of zygoma not obviously thus nicked ...--.| ..---- =e se) een ss oan cen Wied Sel foelaeyseute 
Descending process of mandible: 
A broad, flattened, squarish plate, wholly below 
PO ER oe so SececopeseoSte sch cacesanenans case! + +y)eI]+eI+] +] +i ee] --] -- 7 -- | ee |e 
A narrow, hooked, recurved process, attaining 
LOveLOb MOIS emcesiecasciseesees caste sera |lmaanes we [ese Pear | ons [een emi tel ete pert ulestan betas 
Coronoid process of mandible: 
Well developed, acute : 
Not as high as condyle. afew meal met f) S| fesceall dma] ete ere a Pate Meera eee lesa | ee 
As high as condyle........-.....-..--.--- + +l+]4+]--]--;/ +H 4] 2] +4)4]--] 2 
Tnterparietal : 
Nearly as long as broad, one-third as large as 
TOS ITU We Se aR ee ne oo tecege || ceeads SE Pees SH 54 fhsou| see) od iae Se {fos ce 
Lozenge-shaped or quadrangular, much smaller.| + +) +/+] +] A) 4AY ley al al als 
Parietals ; 
Small, subcireular, with various angles ......-..] ------ weil he nsl| mey | oe tenet meted [tem aa |feeeall lesen [Reel eee tne 
Large, subquadrate, with postero-external ex- 
LENO onmoseractor CS eR ECOncssecandceescaseccns + +l] title] t+ il Fl] 4+i4ai4i4+i-- 
Temporals: 
Hypertrophied, projecting at right angle far 
INGO OLDIES 2. oem sional cece secios = con cweee Fuse cee se maces Pe Wiest sca eel ees! sat Geo eck Sal Pes) ilase |lae 
Moderate, bounding orbits by an obtuse promi- i| 
MONOG | soeawa secre spe ee boas so ehoneewecinaceee Je au +] fe hee |] Ee ES 
Zygomata : 
Styloid, or little expanded..-.......... OspSage + J+l)+y+}+i/4+)/4+i 4)/4+)/4+/4+/4]-- 
Laminar, or broadly expanded .. Allies elec att eeal teeters eet [deen ered tet 
Strongly divergent posteriorly .. SS} Senses SE eR cs ee SSN cell eed econ een Reem nee 
Approximately parallel ................-.. --|--/+] +] +I +i 4) 4+/4/4+/4]4+ 
Descending to the level of the palate..........-. + Pensa feel Pee ee Nees ras lles IP oe los 
Not dropping to the level of the palate..........| ...... +/+] --]--]--]-- |] +) 4] 4/4+]/4]4+ 
Nasals, anteriorly : 
Produced beyond premaxillaries and incisors....| + Fe] p=] |e] SE Se Sa) ce iiceult eetlll eaters 
Barely or not exceeding premaxillaries..........| ...-.. Se eee ee ee ee ee Se eo 
Foramen magnum : | 
Subcircular, trefoil, or higher than broad........| ...... --}--}+) +] 4+] 4+] 4) +] 4/)/+)4+]4+ 
Brosderithan high: .2-cc.c2cscetee ase ece~ on nee + Sal he Sd reese ess oo tesedll  Pseil| cee} seliiss Ices} ce 
