GARMAN: THE CHIMAEROIDS. 257 
species and genera. Three of the known living species are reported from the 
southwestern coasts of South America; the other two are from Tasmania and | 
the Cape of Good Hope respectively. The younger stages of all are similar. 
Callorhynchus callorhynchus, Plate 7, Figures 7 to 9, is the species most widely 
known ; in it the tritor of each palatine tooth occupies the greater part of the 
entire length of the dental plate and sends forward two prongs, the inner of 
the two being the longer. C.smythii, Plate 6, Figures 1 to 4, as already men- 
tioned, has two distinct parallel tritors on each of the palatine teeth. Both of 
these forms occur at Valparaiso and Talcahuano. C. tritoris is a new species 
from the Mejillones; one of its palatines and the vomerines are drawn on 
Plate 6, Figure 9, where the tritor of the first is seen to be placed far back 
on the tooth, to be broader than long and hardly notched anteriorly. In 
C. milii, Plate 6, Figures 7 and 8, the prongs are short; and the tritors have 
a considerable forward extension on the palatine teeth, while the mandibular 
tritor is short, rounded, or oblong, and like those of the palatines situated near 
the posterior edge of the tooth. This is the Tasmanian species first named, 
described, and figured by Bory, 1823, and later described by Richardson, 1841, 
under the name C. tasmanius. Callorhynchus capensis, Plate 6, Figures 5 and 
6, is marked by very slender and sharp forward extensions of the tritors on 
both palatine and mandibular teeth ; these prongs are elongate and tapering, 
and the hinder portion of the tritor on the palatine is comparatively short, but 
on the mandibular teeth the posterior swollen portion of the tritor appears to 
be longer than that of the tooth above it. This species was described by 
Duméril, 1865, from specimens secured at the Cape of Good Hope; the figures 
cited above were drawn from an individual sent by E. L. Layard, Esq., from 
the same locality. Interest in C. capensis is heightened by the fact that traces 
of its existence have been found in Cretaceous formations and in a locality 
which greatly widens its distribution. For the species described by Newton, 
1876, in the Quarterly Journal of the Geological Society, p. 326, Vol. 3, and 
figured and described by the same author, 1878, in the Memoirs of the Geologi- 
cal Survey of the United Kingdom, IV., p. 41, Plate XII., Figures 11 and 12, 
under the name Callorhynchus hectori, from a fossil palatine tooth found at 
Amuri Bluff, New Zealand, in a fine conglomerate, believed to be of the age of 
the Lower Greensand, of the Cretaceous, is not to be separated from C. capen- 
sis by any of the characters at present known. This is the earliest positive 
evidence of the existence of a species of now living Chimaeroid. 
The teeth of Chimaerae are more differentiated than those of any other 
genus of the group. Judging from the dentition, the evolution of Chimaera, 
as in the reduction of the rostrum, would appear to have gone a stage farther 
than that of the species of Callorhynchus, and in doing this to have acquired 
the peculiar laminated structure and the palatine and mandibular tritors on the 
forward edges of the teeth. The ridges on the inner sides of these teeth may 
be looked upon as remains of tritors, similar to those of Callorhynchus smythii, 
Plate 6, Figures 1 and 2. If the rise of Chimaera were to be traced, there 
would probably be found among its ancestors some with teeth like those of the 
