續一切經音義 1.79

1.79

蟣蝨（上居擬反韻英云蝨卵也下所乙反說文嚙人蟲也從卂䖵作蝨經文從卂作虱俗用非也卂音信䖵音昆也）。

Nits and lice (蟣蝨: the first character has the fanqie 居擬 [jǐ]. The Yunying says: "Louse eggs." The second character has the fanqie 所乙 [shī]. The Shuowen says: "An insect that bites humans." It is written as 蝨, formed from 卂 and 䖵. In the sūtra text it is written with 卂 as 虱, a popular usage that is incorrect. 卂 has the pronunciation 信 [xìn]; 䖵 has the pronunciation 昆 [kūn]).