108 MEMOIRS OF THE CARNEGIE MUSEUM 
spines preserved nearly in place, the anterior zygapophyses of these look upward 
and slightly inward, the planes of which if continued to intersection would meet at 
an angle of 160° to 170°. The posterior zygapophyses look downward and some- 
what outward, being separated by a slight vertical depression. 
The neural arches as they rise from the centra are slightly inclined backward. 
This inclination is continued in the spinous process at a still greater angle. The 
spines of the anterior vertebree are greatly compressed laterally, being flattened into 
a subquadrate plate of bone that is somewhat thickened above. Of the spinous proc- 
esses of the posterior vertebrae nothing of importance is shown by the material under 
discussion, though the articular bases of the pedicels must undergo modifications 
corresponding to those that take place on the dorsal surface of the 
centra of the several regions. Anteriorly the base is subtriangular in 
form and somewhat protuberant, but upon the centra where the sep- 
aration of the diapophysis and neurapophysial surfaces takes place 
the articular end becomes long and narrow, and rests upon corre- 
sponding ridges which rise from the dorsal surface of the centrum. 
(See fig. 17, x.) 
Ribs. — Though there are numerous parts of ribs preserved with 
the different skeletons no complete ribs have been found. Those 
pieces lying on either side of the anterior vertebra of No. 878 (see 
Fig. 20. Pos- Pj. VII.) show the ribs of this region to have been very long and 
terior view of a 
right dorsal (?) ‘ : eae! 
rib of Baptano- although both ends are wanting. This evidence appears to indicate 
slender. On the left side of the column (7’) is about 725 mm. long 
don discus (No. a very deep body cavity anteriorly. Corresponding to the form of 
603). One half 
aa the anterior vertebrae the ribs have a distinct tuberculum and capit- 
natural size. 
ulum. ‘he latter probably as in the other groups of the Ichthy- 
opterygia disappears in the posterior dorsal region. As yet the abdominal splint- 
ribs so numerous in Jchthyosaurus have not been observed in this genus. 
Pectoral Arch. — Plate XII., Figs. 1, 2 and 3. 
The pectoral girdle of Baptanodon is represented in two specimens, Nos. 878 and 
919, the former having the most complete arch yet discovered of this genus. 
Fig. 21 shows the inferior view of the elements as they were retained in the matrix. 
The girdle pertaining to No. 919 though incomplete has been entirely removed 
from the matrix and it gives us a good idea of the anterior and superior aspects of 
this region. (See Pl. XII., figs. 1 and 2.) As mentioned previously this specimen 
may prove to belong to a different species when more complete material is known. 
It will be observed in fig. 21, that with the exception of the clavicles and inter- 
