ISMAIL, C.J.

All these four tax revision cases raise a common question of law and they are disposed of by a common judgment. From one point of view, this will be sequel to our judgment dated 29th November, 1979, rendered in Bava Prima Tannery v. State of Tamil Nadu dealing with the liability to sales tax of the purchase turnover of raw hides and skins and the sales turnover of dressed hides and skins under items 7(a) and 7(b) of the Second Schedule to the Tamil Nadu General Sales Tax Act, 1959 (hereinafter referred to as the Act). We are concerned in these tax revision cases with the claim for enhancement of assessment made by the State at the hearing of the appeals preferred by the assessee-respondents before the Tribunal, in each of these four cases. When the appeals preferred by the assessee-respondents were taken up for hearing, the revenue had filed petitions for enhancement of the assessment on the basis that in accordance with the judgment of the Supreme Court in V. Guruviah Naidu and Sons v. State of Tamil Nadu the assessing officer should have proceeded under item 7(a) of the Second Schedule to the Act and assessed the purchase turnover of law hides and skins, made in the State, instead of assessing the sales turnover of dressed hides and skins sold in the State. The subject-matter of Tax Case No. 449 of 1979 is the order of the Sales Tax Appellate Tribunal, Main Bench, Madras-1, dated 29th August, 1978, rendered in Tribunal Appeal No. 981 of 1977 read with Tribunal Miscellaneous Petition No. 302 of 1978. The appeal itself was preferred by the assessee-respondent. The contention that was put forward by the assessee-respondent in the appeal was against the tax at 3 per cent on closing stock of raw skins. However, the revenue filed Tribunal Miscellaneous Petition No. 302 of 1978 contending that the assessing authority had filed to assess the assessee on the entire local purchases of raw hides and skins which went into the production of tanned hides and skins and the purchase turnover was liable to tax at 3 per cent under item 7(a) of the Second Schedule to the Act and such turnover amounted to Rs. 27, 93, 138, that the last purchases of raw hides and skins in this State are assessable only under item 7(a) of the Second Schedule and this is supported by the decision of the Supreme Court in Guruviah Naidu and Sons v. State of Tamil Nadu referred to above. The Tribunal relying upon two decisions of this Court in State of Madras v. Spencer and Company Limited and State of Tamil Nadu v. K. R. and P. Shanmugavel Nadar held that it has no jurisdiction to entertain the enhancement petition at that stage, since such a contention was not put forward and was not made the subject-matter of the appeal before the Appellate Assistant Commissioner. The subject-matter of Tax Case No. 486 of 1976 is the order of the Sales Tax Appellate Tribunal, Main Bench, Madras-1, dated 9th January, 1979, made in Tribunal Appeal No. 903 of 1977, read with Tribunal Miscellaneous Petition No. 96 of 1978. That also was concerned with the liability to tax of the purchase turnover of the raw hides and skins in the State under item 7(a) of the Second Schedule to the Act. In that appeal also, the revenue filed an enhancement petition stating that the turnover of last purchase of raw hides and skins as per accounts of the assessee is Rs. 17, 29, 529, but the assessing officer assessed only Rs. 16, 21, 819 representing the proportionate last purchase of raw hides and skins attributable to export sales and inter-State sales and that in view of the decision of the Supreme Court in Guruviah Naidu and Sons v. State of Tamil Nadu the entire last purchase of raw skins have to be subjected to tax at 3 per cent and, therefore, the turnover of last purchase may be enhanced to Rs. 17, 29, 529. Dealing with this enhancement petition, the Tribunal observed :

"As for the enhancement petition, we do find that the request of the State Representative is for bringin