40 ROY L. MOODIE 
been three other genera referred to the Branchiosauria from the North 
American deposits but there is good evidence that none of them 
belongs here. The genus Amphibamus (Fig. 24) was originally 
referred to the Xenorhachia by Cope? on account of the supposed 
cartilaginous condition of the vertebrae and the absence of ribs. Later 
he abandoned this order and placed the form in the order Branchio- 
sauria where it is retained by Zittel.2 Recently Hay? has shown, 
and I am able to corroborate his statement, that there are ribs present 
in the species Amphibamus grandiceps Cope, and that they are long 
and curved, not at all like the short ribs of the true Branchiosauria. 
These long, curved ribs unquestionably exclude the form from the 
Branchiosauria and indicate its close affinites with the Microsauria. 
The genus Pelion has also been referred to this group on purely nega- 
tive evidence.t The genus is excluded from the Branchiosauria by 
the well-ossified condition of the limb bones, in which the endochon- 
dral ossification is seen to be well developed, a condition which never 
prevailed among the Branchiosauria so far as is known. The form 
of the head and the elongated hind limb would also tend to exclude 
this form from the group. In the Branchiosauria the fore limb is 
usually larger than the hind limb, but in Pelion lyelli Wyman the 
hind limb greatly exceeds the fore limb in length. The genus Spara- 
dus as it occurs in North America has also been referred to this 
group by Lambe.’ In the first place the presence of the genus 
Sparodus in the deposits of North America is so uncertain as to render 
consideration of the form almost unnecessary. The presence of the 
genus is indicated by remains which are almost impossible of defini- 
tion and such a reference as made by Dawson is at the best an 
uncertain one. 
The form, Micrerpeton caudatum, is represented by very complete 
remains ‘(Pal. Coll., U..of ©: Noo12)213)..)) The specimens 
preserved on opposite halves of a nodule from the Mazon Creek beds of 
Grundy County, Illinois. Ina recent conference with Dr. David White 
1 Proc. Acad. Natl. Sci. Phila., 1865, pp. 134-37. 
2 Zittel, Handbuch der Paleon., 1 Abth., Bd. 3, p. 375. 
3 Proc. Amer. Phil. Soc., 1900, p. 120. 
4 Zittel, Handbuch der Paleon., 1 Abth., Bd. 3, p. 375. 
5 Trans. Roy. Soc. Canada, 1904-5, Vol. X, p. 45. 
