Cope.] ^"^-^ [Doc. 2r- 



transverse section would be tliat of a broad wedge with slightly truncate 

 inferior apex. The neural spine lamina is attached in a strong inferior 

 groove of these pieces. The groove becomes wide and shallow posteriorly. 

 At the extremity of the vertebral series there are two isolated rugose 

 elevations, perhaps for the last neural spines. On each side of the last 

 a shallow concavity marks the point of contact of the ilium. 



HOMOROPHtJS INSUETUS. CopC. 



Species nova. 



The mesosternal bone is joined by an openly concave sutural margin of 

 the hyosternals on the lower surface. On the superior face the sutural 

 mai'gins are straight, projecting further posteriorly and forming an obtuse 

 angle. The pectoro-abdominal dermal suture crosses the hyosternals near 

 their middle ; the abdomino-femoral, which is rather obscure, at the pos- 

 terior third. 



The superficial sculpture of carapace and plastron is destroyed. The 

 inferior surface of the costal, displays a marked concavity exterior to the 

 position of the rudimental costal capitulum. The curvature of the costals 

 is well marked. When separated from each other, a fine sutural face 

 forms the inferior third of the thickness, the superior two-thirds being 

 fracture only. There are three vertebral dermal scuta more or less com- 

 pletely preserved. The outline is cofifin-shaped anteriorly ; in one the 

 lateral margins are convex, in another concave, and then expanding again 

 posteriorly, the whole being fiddle shaped (panduratus). The two pos- 

 terior costal scuta meet on the middle line, and the last pair embraces a 

 pygal which is elliptic in front. 



The shell is every where stout, and excessively thick ; neither hypo nor 

 hyosternals being thickened medially. The left hyosternal joins the right 

 hyposternal at the intersection of the sutures. 



M. 



Length hyosternal on median suture 0.095 



" hyposternal " " lO.') 



Thickness " " " 015 



" median costal proximally Oil 



" anterior vertebral 014 



Length '• " 06 



Width do. anteriorly 0285 



" " posteriorly 91 



" anter. vertebral scute anteriorly 035 



Length " " " " 06 



The free edge of the hyposternal is thinned to an edge rather abi'uptly. 

 The last distinct vertebral scutum is wider than the others, a costal suture 

 going off near its posterior margin. 



The slight enclosure of the mesosternal bone gives the plastron a re- 

 semblance to those of Adocus syntheticus, A. beatus, and A. agilis. The 

 last is much thinner ; the second differs entirely in the characters of the 

 vertebral scuta, &c. It is nearer the A. syntheticus, but besides the 



