Wow... very cool looking animal. Maybe Chris H. can chime in but here are some scale counts that might help you figure it out-

Eryx miliaris: Total adult length, males: 12-15", and thin, females ~18-22" (pers. obs.)

subcaudals, 20-32
ventrals, 164-184
midbody scale rows, 43-49
circumorbitals, 10-14
upper labials, n/a

Eryx jaculus: Total adult length, males: 12-15", and thicker than miliaris (pers. obs.), females ????

subcaudals, 19-36
ventrals, 161-205
midbody scale rows, 45-54
circumorbitals, 7-14
upper labials 9-14

Eryx tataricus: Total adult length, males: ??, females 30-36". Male E. tataricus are heavier than male E. miliaris.

subcaudals, 17-45
ventrals, 175-213
midbody scale rows, 45-59
circumorbitals, n/a
upper labials 11-12
lower labials, ~16

Most of this info is from:

Jones, C. 2004. Sand Boas. Reptilia No. 34:12-23.

If I had to guess I would say E. tataricus.

-Chris
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Christopher E. Smith
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