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PETERSON: A REVISION OF THE ENTELODONTID A 99 
importance which they have in the Miocene genus. Back of the second dorsal in 
Dinohyus hollandi the arrangement of these canals is almost identical with that in 
Sus, the vertical canal being even relatively larger. 
The costo-vertebral canals are very narrow but deep excavations, which lead 
directly into these large horizontal and vertical canals, forming an excellent protec- 
tion for the spinal nerves. The keel of the centrum is fully as well developed as in 
the preceding vertebra. In Archevotherium the corresponding vertebra has a heavy 
and rugose area on the anterior half of the keel, but the ventral projection is not 
nearly so great. 
Fourth Dorsal Vertebra.— In Dinohyus this vertebra is more nearly like that of 
the Archxotheriwm skeleton from Princeton than any of the preceding dorsals. The 
vertical diameter of the centra back of the second dorsal in Archxotheriwm rapidly 
increases, so that the centrum of the fourth has about the same proportionate diam- 
eter as in Dinohyus. The arrangement of the foramina through the walls of the 
neural canal, which are sometimes absent in Archxotherium ingens, is the chief char- 
acter showing a difference between the vertebree of the two animals. 
Fifth Dorsal Vertebra. —The top of the neural spine of the fifth dorsal is com- 
plete, but unfortunately the contact is lost at the lower half of the spine. ‘The 
length of the spine is estimated by a gradual slope from the second to the seventh 
dorsal vertebree, which have complete neural spines. ‘The general construction of 
this bone differs go little from that in Archxotheriwm that a description seems hardly 
necessary.” 
Sixth and Seventh Dorsal Vertebre.— With the exception of the broader and 
undoubtedly longer neural spine in the sixth dorsal vertebra, the seventh differs 
very little from it, and the two are so similar to the fifth dorsal that a separate 
description seems superfluous in this connection. With the exception of the per- 
forations of the transverse processes, the deep median furrow near the base and 
rugose surfaces on the anterior faces of the neural spines, and the somewhat more 
sharply keeled centra, there are no differences from the corresponding vertebree in 
Archexotheriwm described by Professor Scott. 
Kighth Dorsal Vertebra.— This vertebra has no ventral keel on the centrum, 
it being quite smoothly rounded below, and consequently having a smaller vertical 
depth than the vertebree anterior to it. The median furrow or groove on the 
anterior face of the neural spine extends well up and is still quite deep on the 
fragment we possess, proving that the spine itself must have attained a consider- 
Tn cleaning off the matrix for a closer examination of the transverse process of the fifth dorsal vertebra in 
Archiotherium ingens, which Professor Scott described, it is found that there is a small foramen on the upper face of the 
neural arch which is apparently connected with the horizontal canal as in Sus. 
