414 ON A NEW SPECIES OF MACRAUCHENIA (M. BOLIVIENSIS) 
behind this tooth, the right half of the palate is marked by what 
might hastily be taken for a suture, but which is nothing but a 
fracture. Behind it, and o-9 of an inch in front of the posterior end 
of the longitudinal suture, two curved transverse lines, convex for- 
wards, which I believe to be the maxillo-palatine sutures, pass into 
the longitudinal suture. 
Thus, it is clear that the palate must have extended back for 1:2 
of an inch behind the third grinding-tooth. 
Supposing this tooth to have been succeeded by three others 
whose length, if they were molars, would be probably between o6 
and 0’7 of an inch, it follows that the posterior margin of the palate 
must have extended, at least, as far back as the posterior margin of 
the second molar. This is further than it extends in the Auchenie 
(the very forward extension of whose palatine aperture is exceptional 
among the Artzodacty/a), but it is not so far as in the Camel, where the 
posterior boundary of the palate is opposite the middle of the last 
molar. 
This backward extension of the palate is, so far as it goes, in 
favour of the view to which the consideration of the dentition and 
the structure of the occiput leads, viz., that the cranium of the 
Macrauchenia was constructed upon an essentially Artiodactyle type. 
The following are the dimensions of the palate and teeth of 
Macrauchenia Boliviensts, and those of the corresponding parts in 
the Vicugna :— 
Macrauchenta. Vicugna. 
Width of palate inside 
the grinding teeth? 
Antero-posterior length ( more than 2°0) 
of four grinders . . | less than 2°5f 
} about ime) 1°25 (at widest). 
. 
iS) 
1 The attempt to differentiate the Artiodactyla and Pertssodactyla absolutely by the 
position of the posterior margin of the bony palate is fallacious. On an average it is 
doubtless true that the bony palate extends further back in the former than in the 
latter; but the bony palate extends to a line joining the anterior edges of the last 
molars in Ayrax; while in the full-grown Guanaco, a similar line is 0'4 of an inch 
behind the posterior boundary of the palate. 
2 The six grinding-teeth of the lower jaw, which Professor Owen has provisionally 
referred to AZacrauchenia (British Association Reports, 1846), are said to form a series 
g inches long. A series of six such teeth of the lower jaw of Alacrauchenta Boliviensis 
could not have exceeded 4 inches in length, and was probably shorter. Under these 
circumstances, the heads (as measured by the teeth) of the two species would be in nearly 
the same proportion as their astragali, and in very different proportions from their cervical 
vertebree. This is not improbable; for the Vicugna has a much lighter head than the 
Guanaco, if the cervical vertebre be taken as the standard. The length of the fourth 
cervical of the Vicugna is to that of the same bone in the Guanaco as 1: 1}, while the 
length of the head in the two is as 1: 14. 
