A NEW FORM OF “DIPLOCAULUS” 53 
distinctly paired. In most cases the depressions are connected 
by a very shallow and narrow groove, but in one or two of the 
vertebrae the openings are distinct. The size of the pits is another 
distinctive feature of this form. Between the lateral margins of 
the pits of the fourth vertebra is a distance of 7 mm. and in 
every case the pits are so large and so widely separated that the 
spine is distinctly swollen for their accommodation. Clearly, 
whatever the function of these pits it was more fully exercised in 
this than in any of the other forms that have been observed. 
As in the typical Diplocaulus, the articular faces of the zygo- 
pophyses are directed straight up and down so that their common 
plane furnishes a plane of reference for describing proportions. 
The zygosphene and zygantrum is strongly developed throughout 
the series of vertebrae. Posteriorly the neural spine divides to 
send strong buttresses down, out, and back to the posterior zygo- 
pophysis. Between these buttresses there extends back in a 
horizontal plane a spoutlike projection, the zygantrum. The spine 
of the preceding vertebra extends forward as a vertical plate 
running in the groove or spoutlike zygantrum without any notice- 
able modification for the articulation. There is a suggestion of 
further strengthening of the intervertebral articulation through 
a more or less pronounced vertical keel between the posterior, 
zygopophysial lamellae at the anterior end of the zygantrum 
excavation. Some of the vertebrae show a corresponding exca- 
vation on the lower anterior edge of the zygosphene extension of 
the spine. 
The following table comparing the various dimensions of the 
present specimen with those of the common type, No. 1018 in the 
Walker Museum Collections, will serve to emphasize the differences. 
W.M. No. 564 W.M. No. 1018 
mm. mm. 
Wenethvotcentrumisere es. soe ae 40 22 
Dist. across transverse processes... .. 70 44 
Greatest height yess: sec eck se ss 40 23 
Belowsplame lot ZyfOue. vse cece s ese 14 12 
NWOWE Nplate Of ZYFOr,\)--4 1s cs e's sae 26 II 
INCLOSSIZV SZ OPOPHMYSESWs 4. cs Ja vied 40 6 36 21 
