Srimad Bhagavatam Canto 10, Chapter 30, Text 25

 SB 10.30.25

padani vyaktam etani
 nanda-sunor mahatmanah
laksyante hi dhvajambhoja-
[The gopis said:] The marks of a flag, lotus, thunderbolt, elephant goad, barleycorn and so forth on these footprints clearly distinguish them as belonging to that great soul, the son of Nanda Maharaja.
Srila Visvanatha Cakravarti Thakura, in his commentary on this verse, gives the following scriptural information about the symbolic markings on the lotus feet of Krsna:
“In the following verses the Skanda Purana states the particular places on His feet where Krsna carries the mark of the flag and also other marks, and the reasons for these marks:
daksinasya padangustha-
 mule cakram bibharty ajah
tatra bhakta-janasyari-
 sad-varga-cchedanaya sah
‘At the base of the large toe on His right foot, the unborn Lord carries the mark of a disc, which cuts down the six [mental] enemies of His devotees.’
madhyamanguli-mule ca
 dhatte kamalam acyutah
‘At the bottom of the middle toe of that same foot Lord Acyuta has a lotus flower, which increases the greed for Him in the minds of the beelike devotees who meditate on His feet.’
kanistha-mulato vajram
parsni-madhye ’nkusam bhakta
‘At the base of His small toe is a thunderbolt, which smashes the mountains of His devotees’ reactions to past sins, and in the middle of His heel is the mark of an elephant goad, which brings the elephants of His devotees’ minds under control.’
bhoga-sampan-mayam dhatte
 yavam angustha-parvani
‘The joint of His right large toe bears the mark of a barleycorn, representing all kinds of enjoyable opulences.’
“The Skanda Purana also states:
vajram vai daksine parsve
 ankuso vai tad-agratah
‘A thunderbolt is found on the right side of His right foot, and an elephant goad below that.’
“The acaryas of the Vaisnava sampradaya explain that since the particular feet under discussion are Lord Krsna’s, we should know that the thunderbolt is at the base of His small toe and the elephant goad below the thunderbolt. An elephant goad on the heel belongs rather to Lord Narayana and other visnu-tattva expansions.
“Thus the Skanda Purana describes six marks on Krsna’s right foot — the disc, flag, lotus, thunderbolt, elephant goad and barleycorn. And the Vaisnava-tosani mentions even more marks — a vertical line beginning at the middle of His foot and continuing as far as the juncture between His big toe and second toe; an umbrella below the disc; at the base of the middle of His foot, a group of four svastikas in the four cardinal directions; at the four points where each svastika meets the next, four rose apples; and in the middle of the svastikas, an octagon. This makes eleven marks on Krsna’s right foot.”
Srila Visvanatha Cakravarti describes the marks on Krsna’s left foot as follows: “At the base of the large toe is a conchshell with its mouth facing the toe. At the base of the middle toe are two concentric circles, representing the inner and outer sky. Below this mark is Cupid’s unstrung bow, at the base of the bow is a triangle, and surrounding the triangle is a group of four waterpots. At the base of the triangle is a half-moon with two more triangles touching its points, and below the half-moon is a fish.
“All together, then, there are nineteen distinguishing marks on the soles of Lord Krsna’s lotus feet.”
Srimad Bhagavatam Canto 10, Chapter 30, Text 24
Srimad Bhagavatam Canto 10, Chapter 30, Text 26