90 Proceedings of the Biological Society of Washington. 



as well as the youngest, the knob is placed very close to the posterior 

 seam, and age appears to make no difference. 



In all the Florida specimens I find two pairs of chin barbels. In most 

 mainland specimens from the United States only the anterior pair is de- 

 veloped, though in some there are indications of a posterior pair. 



The caudal crests of compressed tubercles appear also to be diagnostic 

 of the two forms, in as much as the tubercles of the median series are 

 smaller and those of the lateral series larger as compared with the corre- 

 sponding series in Chelydra serpentina, in which the contrast between 

 the two series is thus much greater. 



In the series before me there are indications of several equally impor- 

 tant distinctive characters, but they must await confirmation by the 

 accumulation of a more extensive material. 



The dimensions in millimeters, of the type specimen, which is a male, 

 are as follows: Total length of carapace, 231; width of carapace, 187; 

 depth of body, 98; length of plastron, 157; width of head, 57; width of 

 bridge, 13. 



Sceloporus woodi, sp. nov. 



Diagnosis. — Lateral scales directed obliquely upwards and backwards, 

 and passing gradually into the dorsals; series of femoral pores widely 

 separated, not meeting on the preanal region; tail cylindrical; head- 

 shields smooth ; distance between base of fifth toe and extremity of fourth 

 greatly exceeding distance between end of snout and posterior border of 

 ear, equalling that between nostril and arm ; about 42 keeled and rnucro- 

 nate scales between interparietal shield and base of tail, about 11 corre- 

 sponding to length of shielded part of head; 15-20 femoral pores; size 

 small. 



Range. — Central and East Central Florida. 



Type. — United States National Museum, No. 48720; Auburndale, Polk 

 County, Florida; Nelson R. Wood, collector. 



Description. — Type: Adult male. Head-shields smooth; two canthal 

 scales between the posterior of which three larger prefrontal shields across 

 the snout; frontal shield divided transversely; posterior frontal in contact 

 with interparietal ; interparietal very large, as broad as long ; parietals 

 small, roughly equilaterally triangular; six transverse supraorbitals, first 

 and sixth smallest, third much larger than the others; large supraoculars 

 separated from frontals and anterior fronto-parietals by a semicircular 

 series of small scales, which is slightly interrupted at the third and fourth 

 (abnormally in this individual), and from superciliaries anteriorly by a 

 double row and posteriorly by a single row of small scales ; six supra- 

 labials, first and fifth separated from nasal and long subocular respec- 

 tively by a single scale; fifth supralabial under center of eye; anterior 

 border of ear-opening protected by three projecting, pointed scales, the 

 two upper ones quite large; dorsal scales larger than ventrals, sharply 

 keeled and mucronate, with a distinct notch on each side of point, in 

 parallel series; about 42 scales along middle line of back from shielded 

 part of head to base of tail ; 12 scales in middle of back corresponding to 



