166-b 



THE EXTINCT BATRACHIA, REPTILIA 



TAPHROSPHYS STRENTTUS, Cope. 

 This, the largest of our extinct Pleurodira, is represented by portions of three Individuals. 



The largest has been much broken up by the workmen, and many parts of the carapace and plastron are recogni- 

 zable in the larger and smaller fragments. 



The various elements are of great thickness, proportionately as well as absolutely, so that this is the most mas- 

 sive as well as largest species of the genus; in two of the specimens the episternals are considerably thickened at the 

 anterior suture, a, feature not seen in the next stoutest species, T. molops. In the first specimen, the costals liavo the 

 longitudinal reticulate sculpture ; the marginals close reticulate, and the sternal bones are openly reticulate. The in- 

 guinal costal articular groove is characteristic, instead of lying in one plane as in other species, it occupies I lie crest 

 of a ridge which ascends proximally to a considerable elevation, resembling in this, the pubic scar of T. molops. It 

 is, however, nearly smooth wil bin and has no distal boundary; the fact of its being on the middle line of a costal bone, 

 tixes its character. 



One of the elements of the plastron at one of I lie siiturnl angles, cxhibiis an extensive overlapping, or squamosal 

 suture, to the extent of half the thickness of the bone, and distance of M. .028. The articular extremities of the two 

 scapula; arc remarkable for their size. The forms of the mesostemum, and marginal bones of the bridge arc unknown. 

 The anterior marginals are thick and of coarse cellular structure. The posterior arc thinned out to an edge. 



M. 



Width of ordinary costal, 0.001 



Thickness '• " .015 



Width costal bearing inguinal groove, .084 



Thickness " " " .015$ 



" " at proximal part of groove, .0<J7 



Diameter articular and scapula, -005 



" glenoid cavity (transverse), .044 



Thickness epistcrnal at median suture, -02<i 



General uniform thickness of hyposternal, -018 



Of the second specimen numerous portions of carapace and plastron, with head of femur and ooracoid, furnish 



various characters. 



The costal bones are marked with shallow grooves, more closely placed than in Taphr. molops, and with less 

 transverse inosculation. The marginals are rough from the reticulate sculpture. The abdominal surface presents a 

 i oarser and less distinct sculpture of the same kind; its dermal sutures are also distinct. 



The pubic scar is lost, but tbc ischiadic remains. It is obliquely oval, and very near the margin of the deep pos- 

 terior notch of the plastron. Anterior and exterior to it is the shallow fossa, seen in the same position in T. strenuus. 



The anterior lobe Of the Sternum has convergent margins, but, is broadly truncate; in front, each hall' of the margin 

 being slightly concave. 



The point of union of the episternals is prominent, upwards and forwards. The margin of the posterior part of 

 I lie epistcrnal, and anterior part of the hyosternal, is rather thinned out, without intermarginal ridge. The suture 

 between the two is al right angles to it, and at a. little distance from it, it turns forward. 



All the bones are thick except the costals, and the spongy layer is vesicular. The sutures of the costals are smooth 

 and dense, except opposite the spongy layer. 



The femur is characterized by the wide expanse of its trochanters and slenderness of its shaft. The planes of the 

 former make an angle together ofover i)0". The greater is nearly continuous with the head. The ooracoid has two 

 short sutural, and one cotyloid articular faces; its shaft is contracted and slightly curved. 



In. Lin. 



Width plastron in front, f) 1-5 



" " at hyo- episternal suture, 12 1.5 



" from mesosternal to front margin, 20. 



" costal, 2" 8.5 



