892 The Condylarthra. 
necting concretions or overlapping them (PI. xxvi, Figs. Sand 
or underlying them. 
he peculiarity noticed in many of the concretions of ie 
apparent growth upward by films or from a side, is analogous to 
the habit of crystallizing fluids which begin to form crystal 
along the line of attachment, and this in some cases seem depen- 
dent on the lamination of the clay beds. 
It is singular, and I find Professor Hitchcock makes the same 
observation, that in the Fontainebleau limestone, with as much 
or less carbonate of lime in their composition, the calcite has ca 
ried the sand into its rhombohedral forms, which it has failed to 
points through a plastic mass of clay. 
Note.—In Pl. xxvii, fig. 8a is the under view of fig. psf 
surface, 
10: 
THE CONDYLARTHRA. 
BY E. D. COPE. 
(Continued from page 805, August number. J 
PHENACODONTIDÆ. 
PHE genera of this family display a uniformity in the | 
ture of the true molar teeth not seen in the Peri y€ 
Their range of grade is seen in the premolars, 
the superior series. Thus in Protogonia, all o ; 
but a single external lobe. In Phenacodus the cn 
external lobes. In Diacodexis the second, third an and fo K 
have two external lobes. The premolars are unknown a 
codon. While Protogonia is primitive in its superior pre" | 
1 It is necessary to notice two errata which occur in the part of this ari 
published in the last number of the NATURALIST. In pay 
order Hyracoidea, page 792, line 10, fibula is printed inst ‘side ditrigons 
error occurs on page 793, line 13. Second, the figures of - 
natural size, and not two-thirds of it, as stated, 
