250 
TEJiTIARY YERTEBEATA OF TJIE EAYOif, 
that Fraas’s restoration of the snout is correct) the distance of the posterior border of 
the nai es tioin the occipital ciest Avould be represented by 70, in l^i'oz€U(i],o(Ioii by 
03, and in Zeuglodoa oslris by 51. Other points in which this skull differs from that 
o{ J’rotocetiis m-c: (1) the rostrum is much broader and more massive, and does not 
narrow suddenly in front ofyun. 3 ; (2) the nasals are rather shorter and are separated 
posteriorly by a ])rocess of the fi'ontals ; (3) the supraoccijiital surface is perhaps a 
little less concave from side to side, krom the skull of ZciKjIodou osins this form is 
also distinguished by: (1) a relatively rather stouter rostrum and generally more 
heavily built skull ; (2) the possession of much longer nasals, separated posteriorly 
hy a process of the frontals — this nasal process of the frontals does, however, exist in 
some species of the genus (see J. Muller, pi. vii. fig. 2); (3) having a very much 
less concave sipiraoccipital surface ; (4) the greater inflation of the cranial region 
of the skull. 
A plaster cast of the brain-case, taken from an imperfect skull, agrees fairly well, 
Text-fig. S2. 
Palatal view of left jireinaxilla and maxilla, with p»i.3 and pm. 4, of I’rozcuf/hdon airor. 
c., alveolus of canine; fossae for the recepbon of the points of the lower teeth; i. 1-3, alveoli of the 
incisors ; ?.»•., inner roots of 3 and 4 ; iti. 1, first molar ; 7>uv., maxilla ; jim. i-4, premolars or their 
alveoli ; pmx., premaxilla ; s., suture for union with palatiue. g uat. size. 
SO fixr as it goes, witli a natural braiu-cast described by Dr. Elliot Smith in his [laper 
on the “ Brain of the Arclucoceti ” In this he states that the natur.il cast differs so 
far from the artificial cast taken from a skull of Ztiiglodon osu'is that it must have 
belonged to an animal differing generically from that form. 
I'jtper Dentition (FI. XXL figs. 1 .v, lit; text-fig. 82). — There are three incisors, 
which, judging from one of which the crown is well preserved, were conical sharp- 
pointed teeth directed somewhat forwards. The crown is somewhat compressed 
laterally, and there is a slight keel on the anterior and posterior borders; the enamel 
at the base of the crown is raised into fine ridges, 'i'he first incisor is situated at the 
extreme anterior end of the premaxilla, the others follow at intervals of about 1'5 cm. ; 
*■ Pi'oc. Roy. yoc. vol. 71 (1903) p. 322. 
