148 



DR. R. W. SHUFELDT ON 



[Apr. 1, 



(Plates XVI.-XVIII.) 



Contents. 



Page 

 I. Introductory Remarks ... 148 

 II. Form and External Cha- 

 racters 150 



III. Myolugy 158 



IV. Contained Organs of the 



Coelora 192 



V. Thoracic Organs 201 



VI. Oral Cavity 203 



VII. Poison-glands 206 



VIII. Olfactory Cavities and 



Organ of Jacobson 207 



IX. Anatomy of the Eye 208 



X. Anatomy of the Ear 209 



XI. Arterial System 210 



XII. Nervous System 211 



XIII. Skeleton ." 214 



XIV. Summary 231 



XV. Concluding Eemarks 233 



XVI. Bibliography 235 



I. Introductory Remarks. 



During the summer of 1887 the present writer came into possession 

 of two very fine Uving specimens of Ilelodenna suspectum that had 

 been obtained for hiin in Southern Arizona, in that section of tbe 

 United States zoogeographically known as the Sonoran Region, and 

 where the natural habitat of this, by far the largest of all of our 

 North-American lizards, is located. 



Never having been so fortunate as to have enjoyed the opportunity 

 of studying the habits and life of tlie Heloderm in its native haunts, 

 I can add nothing here to the accounts of others already published ; 

 nor am I familiar with the mode of reproduction in this interesting 

 species of lizard, though I have heard it stated, by good observers, 

 that it is an oviparous reptile. The two living specimens above 

 referred to were separately packed each in a small box, and in coming 

 to me arrived in excellent condition, after making a journey of several 

 hundred miles, lasting six or eight days, and each lizard consuming 

 only on the day of starting part of a boiled egg. Upon being removed 

 from their boxes they drank freely of water, and afterwards each ate 

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