Natyashastra
एवंविधैः प्रकर्तव्यं रङ्गशीर्षं प्रयत्नतः । कूर्मपृष्ठं न कर्तव्यं मत्स्यपृष्ठं तथैव च ॥ ७२॥
In this way, the stage should be constructed with effort, and it should not have a turtle-shaped or fish-shaped base.
english translation
evaMvidhaiH prakartavyaM raGgazIrSaM prayatnataH । kUrmapRSThaM na kartavyaM matsyapRSThaM tathaiva ca ॥ 72॥
hk transliteration by Sanscript