G. E. Wieland — On Marine Turtles. 327 



angles, the various elements of the present in reality excep- 

 tionally fine fossil do not appear to have been much displaced 

 in their original chalk matrix. This had been removed, how- 

 ever, and aside from the neurals, which remained for the 

 greater part solidly articulated, any clues to form and organ- 

 ization afforded by position in the matrix had been thus 

 destroyed before the specimen reached the Yale Museum. 



Despite this crushing and dissociation of parts, as the result 

 of a careful joint examination by the Museum preparateur, 

 Mr. Gibb, and the writer, it has nevertheless proven possible 

 for the former to make a very handsome and successful mount- 

 ing of the fine carapace with the considerably restored plas- 

 tron in its approximately natural position, as illustrated on 

 Plate X, and figures 1-3, and 6, 7. In fact it is owing to the 

 presence of the nearly complete hyo- and hypoplastron that 

 we are enabled to determine the true width of the carapace, 

 which is indicated in the corrected drawing (figure 1) based in 

 part on the measurement thus obtained. The specimen itself 

 is mounted more nearly as removed from the chalk matrix, 

 the width being somewhat exaggerated by compression. For 

 it was at once decided that it would be far better in mounting 

 the specimen to adhere nearly to the form that had resulted 

 from crushing in the matrix, rather than to distort the junc- 

 tions of the several elements in an effort to reach the elongate 

 form Toxochelys Bauri really had. The restoration is accord- 

 ingly, although at first sight indicating a considerable length 

 of shell, not nearly so narrow and relatively long as originally 

 in life, — an interesting fact because this is almost the only 

 marine form with a carapace suggestive of the great length 

 seen in Dermochelys. 



Description of Parts. 



As the main features of the anatomy of the carapace appear 

 in sufficient detail in the summary of characters and measure- 

 ments given below, taken in conjunction with the accompany- 

 ing figures and plates, we may pass on to a discussion of the 

 special or unique features of interest, namely the nuchal, the 

 epi-neural spines, and the pygal region. 



Nuchal. — The Trionychid-like fontanelles at the junction 

 of the nuchal, first neural and pleurals (figure 1, f), are circu-. 

 Jar to slightly elliptical, and l cin in diameter. Such have not 

 been hitherto observed to occur outside the Trionychids, and 

 with the general form of the nuchal suggest a certain connec- 

 tion with original lines less distant from the Trionychid stocks 

 than are the Cheloninae. Elsewhere the writer has suggested 

 that the Nuchal and Epiplastra of Dermochelys, Protostega, 

 and the Jurassic Thalassemyds may go to indicate a yet 



