BUFFALO SOCIETY OF NATURAL SCIENCES 11 
ward:! “Their histological structure is so different from that of 
any teeth known that their affinities are quite undeterminable. 
They are apparently formed of structureless concentric lamellae 
without any trace of vascular canals or capillaries and the sub- 
stance of the fossils is chiefly carbonate of lime. Some Conodonts 
consist only of a single cusp; others of a series of cusps upon 
one base; and minute plates, ornamented on one side with tuber- 
cles are sometimes found in association with them. They may 
even be the teeth of unknown Nudibranches or Annelids or the 
hooks of Cephalopods, and can thus be dismissed as fragments 
too inconclusive for consideration here” (as the teeth of verte- 
brates). 
It is true that in form and in certain details of internal struc- 
ture, Conodont denticles recall conditions in the teeth of recent 
Annelids. Thus in the modern Nercis,? the inner portion of 
the tooth is darkened by a black pigment. ‘This is also the case 
with certain Conodonts, as for example, that shown on Plate ITI, 
fig. 8, where a vertical view of three broken denticles exhibits 
the same pigmented interior. 
Zittel and Rohon? list a number of forms of Conodonts resem- 
bling the teeth of various recent Annelids; and there is a very 
striking similarity between the tooth of Halicryptus figured by 
them and the Conodont illustrated on my Plate ITI, fig. 10. 
Fractured surfaces of Conodonts, like the cleavage planes of 
crystals, have the same lustre as the normal exterior. 
I tieure on Plates XM, XT and XV certain fragmentary, 
ornamented plates which may have formed the defensive cover- 
ing of these mysterious animals. The plates are always broken, 
rarely exhibiting a natural contour. They, like the Conodonts, 
are composed of structureless carbonate and phosphate of lime* 
and have the same fine, polished submetallic or resinous lustre. 
The upper surface is sculptured with curved and subparallel 
‘Vertebrate Palaeontology for Students of Zoology. Cambridge, 
1898. 
“Compare Rohon and Zittel, Loc. cit., Plate II, fig. 9. 
BICOC cite panos 
*They give with the molybdate of ammonia test a very strong 
phosphatic reaction. 
