1915.] 



NATURAL SCIENCES OF PHILADELPHIA. 



127 



or one may be subdivided and the other not (Nos. 6,408 and 6,411). 

 Between the internasals and the rostrum appear two plates, usually 

 unsymmetrical, and apparently twisted out of position. Their 

 longest diameter may be transverse (No. 6,412) or longitudinal 

 (No. 6,413), and there is sometimes found a third plate in the row 

 (No. 6,409). 



In spite of the fact, however, that all of these median plates of 

 the head may be so irregular, so twisted from a bilateral condition, 



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Fig. 2. — Sceloporus undulalus Latr. Plates of the head. 



SO confusing in arrangement, and so liable to subdivision, it might 

 be pointed out that the series of rows is comparatively uniform. 

 The hypothetical arrangement of the most simple condition might 

 be represented by the figure (fig. 2), and from this arrangement all 

 of the variations shown could be developed. Whether such a simple 

 arrangement would represent the most generalized form or not 

 would be a matter of conjecture. 



12. Ophisaurus ventralis Linn. Fig. 3. 



Three specimens of Ophisaurus ventralis were taken in the Oke- 

 finokee. The Lees, however, report that this lizard is not uncommon 

 and call it the ''grass snake," giving as an explanation of the name 

 the fact that they have noticed that its locomotion appeared difficult 

 ■except in grassy places. They apply the name "joint snake" to an 

 entirely different reptile, which they describe as having joints around 

 the body and which may be Rhineura floridana, although no speci- 

 mens were seen of this form. The three specimens collected were 

 taken in the grass on Billy's Island, but no data were secured as to 

 their life history or habits. 



The two smallest specimens are quite different from the third and 

 largest and may be discussed first. These specimens measured, 



