HOLLAND AND PETERSON: OSTEOLOGY OF THE CHALICOTHEROIDEA. 249 
PIGANSV.ETSO IAI CUETO le les ate. < cee gs cuss, ers sunysvererscamscn ota royale Sem MED sua wie vevar 12 
Antero=posterion diameternol Ps, <n.4.-5.2 5 cietce sata si sie cleat ayia = aleps) anne chee 25 
PRANISVELSERGIAIMELEI: Oli braic ve teuases siete fois Se (os ee ed oo Te cosets asievens 16 
Antero-postenondiameterolm4-o nce an see eens nen ooo ancien 28 
PAM SV ELSE AIMeLEryOLa barr sic iscis et rarer Scar aine Nea ae coe atare ahaleieoaeioe rene 20 
Antero-postenondiameteriot Mate eee rneniiice yc sia: otis ieee gs 36 
AN ENON ESS CHENG OTN Fipas cate paces Biite Ot oe oie OUR Oe THC ee nae 24 
Antero-posterior diameter of Mz. ............ 0. cc eee eee ee eee eens 47 
sRransversediaMmererrOle Vis. wae cenciotoniets ceteris stoi Ac + Halie sen oan ae Dill 
Antero=posteriondiameer of Mgniecne s siecare seein ec come. ence cece ss 53 
Hrans verse GiamevenOl Nisa ancis aks ae vate eo eras cia utes bat sd sklnebendia alia 29 
The Deciduous Dentition. 
(Plate LI.) 
M. peterson Holland (No. 1707). 
A number of individuals in the collection represent the deciduous dentitions 
in different stages of development. The greater portion of a cranium, No. 1707,” 
has the milk-teeth perhaps most completely preserved. D? has a much greater 
antero-posterior and less transverse diameter than the permanent tooth. This is 
chiefly due to the prominent protostyle, which forms a sharp crest on the antero- 
external angle uniting with the protocone, thus presenting a long ectoloph. In- 
ternally there are two tubercles, the posterior the more prominent and separated 
a 
tA \ 
SESS 7M N\ \ 
BA Vit \ 
AWA \ 
\\ 
SS 
UN, 
Vic. 17, View of right side of skull of M. petersoni (No. 1707). X34. 
2” This cranium was described by O. A. Peterson in the Amer. Naturalist, Vol. XLI, 1907, pp. 733-752. 
