ST 



ends of" the teeth l)rokeii oil'. The alveoli ot the Iwo jaws iiifliiic ;i1 a iiai row 

 angle to each other; hence the teeth, which iiltciiiatc, cross each other near 

 the middles of the crowns. The purls preserved appear lo l)eloiiir 1o the 

 premaxillary bone, though no suture can be found, and the bony walls are so 

 thin as to render their ol)literation a probability. There is a keeled ridge 

 along the middle line above, which is not continued to-fhe margin of the l)one. 

 The form of the muzzle is narrow; tlie sides subparallel near the tip. which 

 is elongate rounded. The mandil)ular synipiiysis, iiowever, is not very elon- 

 gate, as the rami are given otf at three inches from the tip. The latter ap- 

 |)ear to iiav(; l)een quite slender from tln^ various small sections or pieces sent 

 with the nuizzle The premaxillary border of 4 inches 7 lines exhibits eight 

 teeth, or their alveoli, of which tlie median two are close together, and not sep- 

 arated by any mandibulars. The sections of the teeth are round or oval, and 

 their sizes are irregular, jirobably on account of dilfering age and degrtu; ol 

 protrusion. The diameters at alveolar margin vary from 6 lines to 3. Their 

 form is slender conic, or, with the root, slender fusiform, and the pulp-cavity 

 is small and median, sometimes cylindric, and sometimes narrowed. The 

 surface, from a short distance above the alveolar margin to the tip, is marked 

 with acute, threadlike ridges, which are sometimes interrupted, and .sometimes 

 furnished with short branchlets. They are more or less undulate, and do not 

 unite, but simply cease as the tip of the tooth is approached. The latter is 

 smooth without lateral cutting-edges. The width of the mandible at the 

 commencement of the rami is 3 inches 0.05 line; of the muzzle of the 

 seventh tooth, 3 inches 7.5 lines; at the third tooth, 2 inches 4.2 lines. 



General liemarks. — The tail is a powerful swinnning-organ, more or 

 less compressed in life: hence the specific name, which means tlat-tailed. 



The dang(!r of injury to which such an excessively elongate neck has been 

 exposed wouhl render the recovery of a perfect sj)ecimen like the present an 

 unusual accident. The neural spines of the dorsal region are so elevated and 

 (dosely jdaced as to allow of little or no vertical motion of the column down- 

 ward ; while, those of the cervical and caudal region being narrower, the 

 elevation ol tiie head is (pate possible, and an upward ilexure easy. 



The iiabits of this species, like that of its known allies, were rapacious, 

 as evinced by the numenius caniiielike teeth, and the tish-remains taken 

 from beneath its vertebra?. The general Ibrui of tliis reptile was that of a 

 serpent, \sitli a rejalivi-ly ■shorter, more rolmst, and nmre posteriorly-plnccil 



