C. W. Gilmore — New Species of Baptanodon. 195 



sides of the centra, at the same time constantly approaching one 

 another, for example, on the anterior vertebrae these processes 

 are 16 mm apart but on the thirty-eighth they are only 7 mm . On 

 the fortieth centrum the dia- and parapophysis are united form- 

 ing an oblique elongated process, 22 mm long and 12 mra wide, 

 which occupies a position well down under the side of the cen- 

 trum. The single process continues as far posteriorly as the 

 sixtieth vertebra : here there is another change. In diameter the 

 single processes on sixtieth to the sixty-sixth vertebrae (inclusive) 

 are nearly double the size of those in front, but they do not pro- 

 ject as far from their centra, and, moreover, their articular ends 

 are deeply concave. These processes also occupy a higher posi- 

 tion on the sides of the centra than either those that precede or 

 follow. 



The single process is found on the sixty-seventh vertebra, but 

 the surfaces of the succeeding centra are so abraded that it is 

 impossible to determine on what vertebra this process is last 

 found. 



Beginning with the eightieth vertebra there is a sudden reduc- 

 tion in the diameter of the centra, or from the eightieth to the 

 eighty-fourth the reduction is more than one half the previous 

 diameter of the centra. From this point the centra gradually 

 decrease in size to the one hundred and fifty-third, which meas- 

 ures f> mm in its vertical and 3 mm in its horizontal diameter. These 

 smaller vertebras are oval in outline and only slightly biconcave. 



The fifth vertebra in the series measures 6() mm in both its verti- 

 cal and horizontal diameter ; the tenth is 90 mm in the vertical and 

 84 mm in the horizontal ; and the fortieth is 109 mm in the vertical 

 and 98 mm in the horizontal. 



The total length of this specimen from the anterior portion of 

 the snout to the end of the one hundred and fifty-third vertebra 

 is 6270 mm ." 



The finding of sucli a complete series of vertebrae estab- 

 lishes definitely the points where the various epophysial changes 

 occur, and the more important of these may he summed up as 

 follows : 



1. The diapophysial and neurapophysial articular surfaces 

 confluent on the anterior vertebras separate on the eighteenth 

 centrum. 



2. The dia- and parapophysis unite on the fortieth centrum 

 to form a single process. 



3. The greatly modified processes on the sixtieth to the 

 sixty-sixth centra (inclusive) may, as Mr. Reed has suggested, 

 represent the point of attachment for the pelvis. 



4. The sudden decrease in diameter of the caudal centra 

 begins with the eightieth vertebra. 



It is now fairly well established that Baptanodon, as in 

 Ichthyosaurus, had a downward deflection of the caudal verte- 



