PYTHON OMORPHS. . 403 



The Pytlidiiciiniirplis, though i)Ccasioii:illy fnuiiil in European <k'])osits, aro best 

 known from Anie'rican specimens, wliicli are aljundaiitly found in the limestone rocks 

 of Kansas and the cretaceous deposits of New Jersey and Ahibama. A careful 

 examination of the fragments has shown that the animals were greatly elongate ; the 

 head large, flat, and cotiieal ; the eyes, tliougli ])laeed at the sides of the head, being 

 directed more or less ujiward ; anil the liml)s represented by two pairs of broad pad- 

 dles, firmly unitcil with the body. In several particulars these ancient forms resemble 

 the serpents. The teeth were disjiosed in four rows along the upper jaw, though dif- 

 ferently arranged, for although the jialatine and maxillary bones were armed, the j)re- 

 maxillar} teeth appearrd in two rows instead of one. They were used only as organs 

 for Seizing the i)rey, wiiieh was swallowed whole, without mastication. The lower 

 jaw had not the l)ones connecting it with the head movably articulated and allow- 

 ing displacement, though the rami were united in front by the elastic ligament so 

 characteristic of the previ(jus order. The distention of the mouth was provided for, 

 however, by a special structure only represented in a few serpents and in the young 

 of some birds, like the heron. This consisted in the jaws being jirovided, midway 



Fio. 233. — Jaw o£ CUdastes ; x, sphenial articulation. 



of their length, with a hinge, the splenial articulation, which enabled the rami to 

 bow out and allow the most bulky prey to gain easy access to the large and spacious 

 gullet. 



By reference to the figure of C/idasti's, it will be seen that the pectoral arch con- 

 sisted of only a scapiUa and coracoid, and that the pelvic arch had no rigid sacrum, 

 and was but loosely united on the middle line below. The ilia were long, and not im- 

 mediately in contact with the vertebral column. The pubic and ischiatic bones were 

 small and free. The pes and nianus, and both limbs, were small in proportion to 

 the size of the animal, and of a less robust type than in any other order of marine 

 Reptilia. 



The quadrate bones movably attached to the sides of the skull, the simple articu- 

 lations of the ribs, and the free vertebras of the sacral region, are points which luiite 

 Pythononior]iha with (^phidia and Lacertilia. The general structure of the posterior 

 [lortion of the lower jaw is like that of lizards, while the chevron bones, j)rotectiiig 

 the sub-eaud.al continuation of the aorta, are not ojihidian. The teeth, being without 

 true roots, arc not like those of Lacertilia, nor are they identical with those of Ojdudia. 

 It will be seen that the animals require an intermediate ])osition between the 

 previous order and tln' one succeeding, the Laeertili.-i. With the otliei- orders, 

 except the Chelonia, which they resemble in having the ipiadrate bone j)artly 

 enclosing the auditory meatus, and a few jioints resembling the Plesiosaurs, they have 

 little or no affinity. 



The genus CUdastes is re)iresenled by about a dozen species once inhaliiting the 



