1889-] Synopsis of the Families of Vertebrata. 865 
a. Sacral and caudal ribs articulating with neural 
Neck bending in vertical plane, last cervical 
articulating with first dorsal by zygapophyses 
only ; pelvis not anchylosed ; marginal bones 
wanting or rudimental ; Trionychoidea. 
c-c-. Sacral and caudal ribs articulating with body 
of vertebrae only. 
As the last ; but marginal bones present and con- 
nected with ribs, and last cervical and last 
dorsal vertebrae articulating by bodies ; pelvis 
not anchylosed to plastron. Cryptodira. 
Neck bending in horizontal plane, the last cervical 
and first dorsal vertebrcTe articulating by 
bodies ; pelvis anchylosed to carapace and 
* plastron; marginal bones present and con- 
nected with ribs ; Pleurodira. 
The Athccce includes the single family of the Dermochelydae. 
The Trionychoidea includes only the Trionychid?e. , 
The Cryptodira embraces the Cheloniidae, Testudinidae, Cinos- 
ternidae, Dermatemydidai, Chelydridae, Baenidae and Adocidae. 
The Pleurodira includes the Pleurosternidae, Sternothaeridae 
Pelomedusidse, Plesiochelydidae, Chelydidae and Carettochely- 
dids. 
The order Theromora includes six suborders. 
I. Palate closed except posteriorly. 
A temporal foramen ; Placodontia. 
II. Palate open anteriorly for nares. 
A. The coracoid bone large, reaching sternum. 
Dentition abundant ; pubis and ischium plate-like ; 
ribs one-headed; Proganosauria, 
Dentition abundant ; ribs two-headed ; Parasiichia. 
Four or five sacral vertebrae ; centra not noto- 
chordal ; no intercentra; dentition imperfect 
or wanting; obturator foramen minute ; Anomodontia 
AA. The coracoid reduced, not reaching sternum. 
Ribs two-headed ; two or three sacral vertebras ; 
