THE SACRUM OF THE LACERTILIA. 85 



plains collected by W. L. Tower. (3) Teiidae — Cnemidophonis 

 sexlineatus Linne, ten specimens, one adult and nine embryos 

 from Mexico. (4) Agamidae — Draco volans Linne, one adult 

 specimen from the East Indies. (5) Helodermatidae — Heloder- 

 ma suspectiim Cope, one adult specimen. 



The specimens were cleared by the Schultze (1) method recently 

 recommended by Dr. Mall (2) and more fully set forth by Hill 

 (3). The method was adopted at the suggestion of Dr. Lillie 

 and experiments have been made on clearing the young and 

 adult stages of all groups of the Vertebrata except the fishes. 

 The methods used are essentially those followed by Dr. Mall and 

 need not be enumerated here. For a complete statement of the 

 method the reader is referred especially to Hill's paper where Dr. 

 Mall's methods are fully outlined. The Schultze method is an 

 excellent one for demonstrating the intimate relations of the bones 

 and cartilages of small animals and deserves to come, into more 

 general use as a method for laboratory demonstration. 



Among the many recent writers on the lizards Friedrich Sieben- 

 rock seems to be the only one who has a definite conception of 

 the true nature of the transverse processes of the sacral vertebrae 

 of the Lacertilia. Cope with all of his keen insight and his wide 

 acquaintance with fossil and recent reptiles seems not to have 

 comprehended the unique character of the lacertilian sacrum. This 

 seems the more remarkable since Cope did more on the lizards 

 than any other naturalist. Cope's observations, however, are in 

 some respects hasty and much of his work will need thorough 

 revision. As an example of this he states on page 163 of his 

 large work on the reptiles of North America, in speaking of the 

 crocodiles : "There are two sacral vertebrae and no sacral ribs." 

 But in the sacrum of the crocodiles there are no transverse proc- 

 esses and there are sacral ribs. 



Siebenrock in writing on the skeleton of Lacerta simonyi Steind. 

 (4) makes the following statement concerning the transverse 

 processes of the lacertilian sacral vertebrae : " Die Frage iiber die 

 morphologische Bedeutung der Querfortsatze an den Sacralwir- 

 beln der Saurier sieht noch einer entsheidenden Losung entgegen. 

 Nach Gegenbaur (5) konnte man sie sovvohl mit den praesacralen 

 Rippen als auch mit den postsacralen Querfortsatze vergleichen, 



