vertebrse, the first true sacral tending to become a lumbar and the first 

 caudal has become a sacral. The two side are strikingly symiu. tn< :il. 

 The figures giving views from above and below are natural size and 

 include the 24th-28th a 



The other known cases of variation in the sacrum of Crocodilia are, 

 as far as I am aware, as follows : Rheinhardt 1 examined 11 specimens 

 and found 3 abnormal. 



1. Alligator scler ops Schn. : Last lumbar become a sacral ; 23 pre- 



2. Croeodllus acutus: 3 sacrals, 3 plane-convex, 1st caudal concave- 

 convex and bearing a chevron, thus the first caudal has become a saera^ 

 23 presacrals. 



3. Crocodilm acutus: First caudal has become a sacral, 24 pre- 



Baur s reported two cases. 



1. Gavialis gangeticus : 25 presacrals. One intercalated between 

 the 9th and 10th. 



2. Alligator mississippiensis : Last lumbar become a sacral, showing 

 on one side a small sacral rib and which does not reach ilium. 23 pre- 



Baur 3 reported three cases. 



1. Crocodilus acutus: A specimen in the museum at Cambridge, 

 Eng. shows on the right side of the 25th vertebra a strong and separate 

 rib, on the left side the rib is smaller and coossified with the centrum. 

 The 26 shows typical sacral ribs. The 27th shows on the left side a 



1 (Anomalier i Krydsvirvlerne hos Krokodelerne, Copenhagen, 1873, and Sur 

 les an .'i ili« - <les vert, bres -a, r.'e- . he/ les crocodilieus. Jul. de Zoologie T. Ill, 

 No. 4. Paris, 1874.) 



'Zoologischer Anzeiger, IX Jahrg., No. 238, 1886. Osteolog. Not. iiber 

 Eeptilen. 



3 (Zoolog. Anz. XII, Jahrg., No. 306, 1889. Kevision meiner Mittheilungen 

 in Zoologisher Anzeiger, mit Nachtragen.) 



