अन्येषाम् अपि दृश्यते

Here we must follow the usage of the Sishthas. Where the lengthening is not ordained by any of the rules of Grammar, but occurs in the writing of standard authors, there we should accept such lengthening as valid. Thus केशाकेशि, कचाकचि, जलासाद्, नारकः, पूरुषः ॥

Vart:- The final of श्वन् is lengthened before the following दन्त, दष्ट्रा, कर्ण, कुन्द, वराह, पुच्छ, and पदः- as श्वादन्तः, श्वादंष्ट्रः, श्वाकर्णः, श्वाकुन्दः, श्वावराहः, श्वापुच्छः, श्वापदः ॥,