Cope.] 286 [Nov. 20, 



posteriorly, and on the tail form half- rings. On the extremity of every 

 third or fourth gastrostege there is a small black spot, throughout the 

 length to the tail. There is a larger black spot on the sides between the 

 extremities of a few of the cross-bands. The superior border of the sixth, 

 and the adjacent part of the fifth superior labial, is black. On the top of 

 the head are three large round black spots ; one is on the centre of the 

 frontal and one is on the anterior part of each parietal. No cross-bands 

 on the muzzle. The dark cross-bands are only two scales wide on the 

 posterior part of the body ; on the anterior part they are three or four 

 scales wide. The interspaces vary from twelve anteriorly to seven pos- 

 teriorly. 



One specimen ; No. 14268. This species is nearest the T. biscutatw 

 D. & B. in squamation, but differs greatly in coloration from this or 

 any other species of the genus. 



I have given a brief synopsis of the species of this genus in the Pro- 

 ceedings of the American Philosophical Society for 1869, pp. 151-2. In 

 introducing two new species I give another synopsis, the more, as I have 

 received a considerable addition to my material since that date. 



I. Scales in 21 rows ; superior labials nine. 



Head with brown chevrons above ; back with diamond-shaped spots 



T. lambda Cope. 



Head with a lyre-shaped pattern above ; dorsal spots in pairs. 



T. lyrophanes Cope. 



II. Scales in 23 rows ; superior labials seven. 



Top of head black with a white T-shaped spot ; dorsal spots entire trans- 

 verse diamonds T. tau Cope. 



III. Scales in 23 (4) rows ; superior labials eight. 



Top of head brown, with a small brown Y-shaped mark ; dorsal spots 



transverse diamonds, more or less transversely divided by paler 



T. upsilon Cope. 



IV. Scales in 23 (4) rows ; superior labials nine. 



Top of head brown ; dorsal spots numerous transverse more or less di- 

 vided diamonds T. collans Cope. 



Top of head white, with three round black spots ; dorsal spot, few trans- 

 verse undivided black rhombs, with pale edges ... 7'. mlkinsonii Cope. 



V. Scales in 25 (7) rows ; superior labials nine. Top of head with chevron 



bands ; dorsal spots formed of four confluent spots and enclosing a 



pale centre T. biscutatus Cope. 



Of the preceding species I have before me one each of the T. lambda ; 

 tau ; collaris and vilkinsonii. Of the T. lyrophanes there are six speci- 

 mens ; of the T. upsilon six, and of the T. biscutatus four. 



I append a description of the new species T. lambda. The muzzle is 

 rather elongate, as in the T. biscutatus. There are three loreals, and the 

 oculars are 3-3 ; the temporals are 3-4-3-4! The fourth and fifth labials 

 enter the orbit, and the sixth, seventh and eight are higher than long. 

 Pregeneials longer than postgeueials. Internasals small, wider than long ; 



