68 
PROFESSOR OWEN ON REMAINS OF A LARGE EXTINCT LAMA 
premolar (p 3) retained after m 3 has risen into place. The only example of Auchenia 
(an A. vicugna ) in which I have observed this condition I figured, on that account, in 
my 4 Odontography,’ plate 133. fig. 2. The proportions of the retained p 3 in the great 
fossil Lama resemble those in that Auchenia vicugna , but the functional and commonly 
retained last premolar (p 4) is relatively larger in Palauchenia (compare figs. 3, Palau- 
clienia , and 4, Auchenia vicugna, both reduced to f, nat. size, in Plate IV.). 
A caniniform premolar is commonly present in the lower jaw of the Camel and Dro- 
medary in the long diastema between the retained last functional premolar (p4) and 
the canine : I have not observed such premolar in any Auchenia , nor is any mention of 
such made by Cuvier or De Blainville (op. cit. p. 95). In the lower jaw of an Auche- 
nia vicugna in the British Museum (675 a), there is a small hard tuberosity on the alve- 
olar border, a little way behind the canine, which may indicate the former existence of 
a rudiment of a premolar (Plate IV. fig. 4, p 1,1) answering to that developed in Camelus. 
In Palauchenia the rudimental caniniform premolar (ib. fig. 3, pi) seems to be situ- 
ated as in Camelus , but is relatively much smaller than is the caniniform premolar 
(pi or p 2) in that genus. 
The penultimate premolar (Plate IV. figs. 1, 2, 3, p 3) is a longish, slender, straight, 
obtusely pointed cone, rising in contact with p 4, but not attaining the level of the 
grinding-surface; though small (see Table of Dimensions, p. 69) it is relatively larger 
than its homologue, the exceptionally developed rudiment, in the Vicugna (ib. fig. 4, p 3), 
and it may be therefore inferred to have been more constantly developed and present 
in Palauchenia. 
What is more certain is the larger proportional size of the last or functional premolar 
(ib. ib. p 4) in Palauchenia than in Auchenia , the fossil in that respect more resembling 
Camelus, but with a larger size and difference of form of the tooth in question. In 
Camelus the fore end of p 4 is narrow, the outer surface curving inward to meet the 
inner one at a ridge which forms the fore part of that surface. In Palauchenia the fore 
part of p 4 is as thick or broad as the back part, and is flattened, — a modification which 
adds to the probability of the constancy ofp 3 in the grinding-series of Palauchenia. In 
Camelus p 4 has a posterior portion or lobule marked off by an external and an internal 
longitudinal or vertical groove, and the corresponding part of the grinding-surface shows, 
after moderate attrition, a distinct small island of enamel. One cannot help recognizing 
this hind part as the rudimental homologue of the second lobe in the true molars. There 
is a slight indication of the outer posterior groove in Palauchenia (ib. figs. 1 & 3, p 4), 
but no corresponding inner one, and no distinct posterior islet of enamel. One long 
slightly curved fold (Plate IV. fig. I,p4) penetrates the grinding-surface, and the tooth 
represents, as in Auchenia and the true Ruminants, the half, or a single lobe, of the true 
molars. 
These (Plate IV. figs. 1,2, 3, m 1-3) adhere to the type in Camelidce, with minor modi- 
fications resembling those in Auchenia. The outer sides of the lobes (ib. figs. 1 & 3) are 
