vairochana's iconography

In earlier saiddhAntika tradition the iconography of tumburu feature him in company of the 7 mAtR^ikA-s. This is contrast to his own root tantra-s of the vAmasrotas where he is presented with the 4 sister goddesses: the chaturbhaginI. Here is the account from vairochana’s manual:

सितं सौम्यं वृषारूढं
जटाहीन्दु-त्रिदृग्युतम् ।
द्वीपि+++(=चित्रक)+++-चर्म-धरं कुर्याद्
वीणाहस्तं च तुम्बुरुम् ॥

मातॄणाम् आदितो नित्यं
शूल-हस्तम् अथापि वा ।
अनन्तरं तु मातॄश् च
ब्रह्माण्य्-आद्यस्तु सप्त च ॥

He should make Tumburu wearing a leopard skin, white in color, mild and riding a bull, with dreadlocks, a snake, the moon, and three eyes, having a vīņā in his hand, always at the head of the Mothers, and also with a trident in his hand.
Now, thereafter are the seven Mothers, starting with Brahmānī