जात्याख्यायामेकस्मिन् बहुवचनमन्यतरस्याम्

In (a common) name (expressive of) class, in denoting the singular, the plural is optionally used.
The words of this sutra require some detailed explanation. The name of a jati or species, always denotes one, since it is a collective noun, and will naturally take the singular number; by the present sutra such words may take the plural number also. In such nouns of class, the plural number has also the force of the singular. The anuvritti of asishyam does not go further.

It follows from this that adjectives which are not themselves common noun, such as संपन्नः &c., agree with the noun and will also get the plural number. Thus संपन्नो यवः or संपन्ना यवाः; "Full grown barley" पूर्ववया ब्राह्मणः प्रत्युत्येयः or पूर्ववयसो ब्राह्मणाः प्रत्युत्येयाः ॥ Why have we used the word jati in this sutra ? For this aphorism does not apply to Proper Nouns. Thus देवदत्तः Devadatta, यज्ञदत्तः Yajnadatta.

Why have we used the word आख्यायाम्? A word may be a class noun or jati, but it may not be the appellation of a class. Thus the statue of Kasyapa may also be called kasyapa; this is a class noun; but as it is not the appellation आख्या or name of a class, such words cannot take the plural form and still denote a singular sense.

Why do we say 'ekasmin'? When two or more class names are compounded as ब्रीहियवौ 'the rice and barley': the rule does not apply.

Vart:- An exception must be made when a class noun is qualified by a numeral adjective. As एको ब्रीहिः संपन्नः सुभिक्षं करोति.