1915.] NATURAL SCIENCES OF PHILADELPHIA. 125 



The femoral pores are always present, ranging in number from 

 thirteen to fifteen, and sometimes very prominent on the smnmit 

 of a high ridge. 



The plates of the head are clearly defined and easily distinguished^ 

 but in some regions most irregular and complicated in arrangement. 

 The specimens usually show five supraorbitals (in three cases six) 

 separated from the median plates of the head by a single row of 

 small scales and bordered externally by two or three rows of super- 

 ciliaries. The usual arrangement of these superciliaries is in two 

 irregular rows with occasionally one or two plates of a third row. 

 The labial plates appear very uniform, the superior row containing 

 five plates and the inferior six. In one or two of the larger specimens 

 this was increased to 6-7. 



The plates of the median dorsal region of the head, however, 

 present a most interesting variation. It is of interest to note that 

 no two of the specimens taken were alike as to the number and 

 arrangement of the plates of this region, although all were collected 

 in the same locality within a period of one month. A chscussion 

 of these plates is rendered difficult by the fact that the descriptions 

 by various authors differ widely in terminology, and it is not easy 

 to determine upon consistent names for the series of plates which 

 may be found. The occipital is large and polygonal and sometimes 

 subdivided (Nos. 6,408, 6,414, 6,415). It contains the pineal eye, 

 which is always present. This plate is bordered by a row of smaller 

 plates ranging in number from four to seven (cf. Nos. 6,413, 6,417 

 and 6,418). Anterior to the occipital in a small single plate, some- 

 times adjacent (No. 6,410) and sometimes separated by the two 

 anterior plates of the bordering row (No. 6,411). The next plate 

 anteriorly is a large pentagonal or hexagonal plate slightly anterior 

 to the middle of the eye. The next row may consist of two or of 

 three plates. If of three, the middle one is small (cf. Nos. 6,402, 

 6,406 and 6,413). The next plate is large and may be subdivided 

 to form an irregular transverse row. The single condition is shown 

 in Nos. 6,405, 6,406, 6,407, 6,414 and 6,415; the subdivided con- 

 dition in Nos. 6,409 and 6,412. Anterior to this plate, and between 

 it and the internasals, there may or may not appear a row of plates 

 ' (when present usually three) , more or less regular and usually pentag- 

 onal. This row is shown in Nos. 6,405, 6,406, 6,407, 6,415, 6,417 

 and 6,418. The two internasals are comparatively large, very irregu- 

 lar in shape and seldom bilaterally symmetrical. They are almost 

 directly above the nostrils. They may be subdivided (No. 6,410), 



