THE 



AMERICANJOURNALOFSCIENCE 



[FOURTH SEEWs.] 



Art. XXXVI. — A New Niobrara loxochelys y* by G. R. 

 Wieland. (With Plate X.) 



None of the numerous marine, or semi-marine turtles from 

 the Kansas chalk or Niobrara Cretaceous have proven of 

 greater interest than the forms included within the genus 

 Toxochelys. For this wholly extinct American group unites 

 carapacial and plastral characters of the Lytolomas of the 

 Upper Cretaceous of New Jersey with Chelydra-like cranial 

 features, and is well represented by a considerable number of 

 specific forms and variations presenting fairly clear evidence 

 that we have here to deal with a line which independently 

 acquired the modifications of limb structure suiting at least 

 some of its members to a marine habitat. 



Moreover it is very significant that discrete epi-neural ossi- 

 cles somewhat similar to those the writer supposed might be 

 present in Archelon are borne serially either on the neuralia, 

 or over the neural junctions in an order suggesting that they 

 have an ancient history, possibly analogous to the ossicles of 

 somewhat similar form so characteristic of the Crocodilidse 

 and in part the Chelydridse. These ossicles as noted further 

 on were first observed in Toxochelys {serrifer} stenoporis by 

 Case (2) and later more fully described and commented' on by 

 Hay (6, 7, 8). The character of the entire series is, however, 

 now determined for the first time. The idea that such ossi- 



* The "writer's previous contributions, mainly on the marine turtles, are as 

 follows : — 



This Journal, vol. ii, Dec, 1896, pp. 399-412, pi. VI. American Natural- 

 ist (p. 446), 1897. This Journal, vol. v, Jan., 1898, pp. 15-20, pi. II; 

 vol. ix, Apr., 1900, pp. 237-251, pi. II; vol. ix, June, 1900, pp. 413-424; 

 vol. xiv, Aug., 1902, pp. 95-108; vol. xv, March, 1903, pp. 211-216; vol. 

 xvii, Feb.. 1904, pp. 112-132, pis. I-IX ; vol. xviii, Sept., 1904, pp. 183-196, 

 pis. V-VIII. — (In Press, — Protostega ; Memoirs, Carnegie Museum of Pitts- 

 burgh ; Plastron of Protosteginse.) 



Am. Jour. Sci.— Fourth Series, Vol. XX, No. 119. — November, 1905. 

 23 



