1896. | NEW YORK ACADEMY OF SCIENCES. 161 
and probably the rest as well) was tuberculate as in the earliest 
Dipnoans and Teleostomes. 
And it is further evident that the ventral armoring of D. 
gouldi does not differ widely from that of Coccosteus. (Cf. Pl. 
VIII, Figs. 1 and 2.) 
(B.) NorocHorDAL AREA AND VERTEBRAL ARCHES. 
The space formerly occupied by the notochord is clearly appar- 
ent in the present fossil, Pl. VII., NC. And an idea may even be 
obtained of the notochord’s relative thickness, as it passed tail- 
ward from the region of the ventral armoring in the broad space 
margined on either side by the remains of vertebral arches. As 
nearly as the present writer can determine the proportional 
thickness of the notochord in Dinichthys is not widely different 
from that in Coccosteus, although, perhaps, slightly thicker in 
the former type. In neither form have any traces been found 
of vertebral centra. 
The vertebral arches, as shown in the present fossil, Pl. VII., 
NA, HA, have been imperfectly preserved. The following notes 
regarding them may, however, be safely made: They were as 
numerous, relatively, as in Coccosteus; they show a similar 
regional differentiation, and appear to be similar in structural 
regards. On the other hand, they differ from the conditions 
in Coccosteus in being shorter and more uniform in length. 
Their substance, too, appears to have been frailer, and judging 
from the structures shown in several cases, it seems probable 
that these arches could not have been widely different from those 
of Ceratodus, 7. e., cartilaginous internally, the superficial 
layers encrusted with lime. Under these conditions the hemal 
and neural structures would naturally be subject to distortion 
during fossilization. 
The neural arches seem to have tapered distally into a neural 
spine. The fossil shows no evidence that this may originally 
have been a separate element, nor does it show that the neural 
arch had ever appended to it a more distal element. The 
hemal arches, on the other hand, seem to have terminated 
bluntly and to have been capped by a separate spine-shaped 
element (hemal spine?) as seen, for example, at HS in 
Pl. VII. It must be admitted, however, that this jointed ap- 
pearance may have been due to artefact. If anormal character, 
the separation of the naemal spine from the arches becomes an 
important diagnostic character, separating Dinichthys from 
Coccosteus. 
TRANSACTIONS N. Y. ACAD. ScI. Vol. XYV., Sig. 11, June 2, 1896. 
