PLEUROSTERNIDA. 45 
In addition to the families Pleurosternide and Baénidz here treated, and the 
Plesiochelyidz provisionally included, the writer refers to this superfamily with- 
out hesitation the Triassic genus Proganochelys, which has recently been so well 
described by Dr. E. Fraas. SWachoue doubt this genus forms the type of a distinct 
family, the Proganochelyide, characterized by the broad shell, the hinder border of 
which is deeply scallopt, by the extremely broad vertebral scutes, by the series of 
supramarginal scutes in front of the first costals and behind the last ones, and by 
the mesoplastra, which meet at the midline and are enormously expanded at their 
outer ends. The genus Proganochelys is the oldest turtle of which we have any 
considerable know ledge, coming. as it does from the Keuper, of the Trias. Cervical 
vertebre of a genus named Chelyzoon have been described by Huene from the 
Muschelkalk of Germany. They have been supposed to belong to the Cryptodira, 
but there is little reason why they should not be referred to fae Amphichely dia. 
The most recent certainly known member of this subfamily comes to us from the 
Uinta beds of Utah. Pleurosternon miocenum Portis has been described from the 
Tertiary near Lausanne, Switzerland, but it is based on a badly damaged plastron. 
Axillary and inguinal buttresses feebly developt. Plastron aaa not notcht behind; 
mesoplastra usually not narrowed at midline . xe .. Pleurosternide 
Axillary and inguinal buttresses strongly developt; mesoplastra narrowing toward midline.. Baénida 
Family PLEUROSTERNID& Cope. 
A family of Amphichelydia. Carapace with costals articulated to the peripherals by close 
sutures and by gomphosis of ends of ribs. Plastron joined to the carapace by sutures and by 
narrow axillary and inguinal buttresses; the former ascending to the first costal, the latter 
attaining the borders of “hie fifth and sixth costals at their junction. In Feloc helys the union of 
carapace and plastron probably less intimate. Mesoplastrals meeting broadly at the midline, 
not much expanded toward the outer ends. Exposed surfaces of carapace and plastron tuber- 
culated or shagreened. Intergulars and inframarginals present. Skull elongated and pointed; 
the bones mostly finely tuberculated. The cervical vertebra are biconcave. Coracoids 
distally expanded. 
So far as the writer knows, the name Pleurosternidz for this family was proposed 
by Prof. Ek. D. Cope in 1868 (Proc. Acad. Nat. Sci. Phila., p. 282) and was employed 
by him at various times afterward. He regarded it as a family distinct from the 
Baénidew. Both families appear to have been alw ays included by him among the 
Cryptodira. Lydekker (Cat. Foss. Reptilia, 111, p. 205) includes in it the Baénide. 
Baur (Proc. Acad. Nat. Sci. Phila. 1891, p. 428) thinks it better to leave Baéna ina 
distinct family, nearly related to Pleurosternon. “To the present writer each group 
appears to be worthy of family rank. The genus Helochel ys, of the Cenomanian of 
Germany, evidently belongs with the Pleurosternide. Pleurosternon is found in the 
Purbeck and Portland Oolite of England. A species described by Roemer as 
Emys menket, from the Wealden of ‘Germany, is believed to belong to Pleuro- 
sternon. Portis has described P. miocenum from the Tertia ary near Lausanne, 
Switzerland. In our own country, it appears that Glyptops existed from the 
Upper Jurassic through the Lower Cretaceous (G. celatus) and the Benton (G. 
pervicax) into the Denver (G. depressus) of the uppermost Cretaceous. 
Genus GLYPTOPS Marsh. 
Carapace deprest. Exposed surfaces of the shell rough with small tubercles and twisted 
ridges. Neurals hexagonal, with the broad end in front. Costo-marginal sulci mostly below 
the costo-peripheral sutures. Axillary buttresses reaching border of first costals. Inguinal 
buttresses each entering an excavation at lower borders of fifth and sixth costals. Mesoplas- 
