AND AVES OF NORTH AMERICA. 



159 



1 



aa No azygus bono in front of caudal marginal. Prochonias. 

 Mesosternum transverse, intergular scute extending to its posterior suture; first ver- 

 tebral scute elongate backwards; shell thin; pubic scar wide, not elevated; inguinal cos- 

 tal pit plane, xiphisternum thin edged ; size medium. t. longinuchtts. 



Mesosternum longitudinal, narrowed; first vertebral scute shortened; costal bones 

 reticulate sculptured; pubic scar long, narrowed, not elevated; inguinal costal pit plane; 

 xiphisternum thin edged ; size large. T. sulcatus. 



"■"-"■ Posterior vertcbrals not known. 



Mesosternal bone as broad as long; the intergular scute not reaching its posterior 

 margin; first vertebral scute shortened; inguinal costal pit plane; shell thin; size 

 smaller; pubic scar wedge-shaped. T. lesliantjs. 



Mesosternal 1 costal hones reticulate or parallel grooved ; inguinal costal pit elevated 

 inwardly, descending to usual plane distally, its fundus keeled; xiphisternum with thick 

 obtuse margin behind; shell thick, vesicular inferiorly ; very large. p. strenuus. 



Carapace thin, surface sculptured with tubercular, ridge-like or vermiform prominences 

 in strong relief ; angle of bridge obtuse ; size large. p. nodosus. 



father Prochonias or Taphrosphys may hereafter be found to be identical with Botb- 

 remys, Leidy. 



TAPHROSPHYS MOLOI'S, Cope. 



Large, stoat; oostal bones, :!.(! Inches in thickness at their proximal portions; the posterior narrower than the ante- 

 rior, and thinning out exceedingly at their extremities. Hyosternal :!.(! lines fehiok behind, costal plates with longi- 

 tudinal grooves, marginals and parts of plastron reticulate, other parts of plastron open reticulate, or with inosculating 

 strise. Proximal end of anterior rib-plates very coarsely reticulate. Vertebral scutes large, as broad or broader than 

 long, with straight margins. Some of the costal capitula small, others large, those of the first pair with a. high pro- 

 jecting keel alongside of them, which. have sutural extremity next Hie vertebra. 



This species is indicated by many specimens. Among these may be, mentioned a. large part of flic carapace and 

 plastron of an individual from near Barnesboro, fewer parts of another from Gloucester County, New Jersey, and 

 part of the carapaoe of two others from Birmingham, Burlington County. A.lso, one costal and two sternal bones, in 

 the possession of the State Survey of New Jersey, at New Brunswick, from the middle green sand bed of Tinton Palls, 

 Monmouth do., N. .1., with fragmentary specimens from various other places. 



These show the species to have been more massive than the P. sulcatus; all the pieces, but more especially the 

 costal bones, are thicker and heavier. 



The first costal bones are remarkable for a. deep curved elongate pit with raised edges, for the purpose of receiving 

 the upper extremity of the hyosternal axillary buttress. It is deepest posteriorly, and is curved forwards and in- 

 wards. The distal margin presents two outlines, both thinned out and in contact with a, marginal by a weals squamous 

 suture, without any gomphosis. Indeed, the recurrent pari of the margin, which formed a notch in thedisc, was uol 



