Reference for Chullin 9:6

בֵּיצַת הַשֶּׁרֶץ הַמְרֻקֶּמֶת, טְהוֹרָה. נִקְּבָה כָל שֶׁהוּא, טְמֵאָה. עַכְבָּר שֶׁחֶצְיוֹ בָשָׂר וְחֶצְיוֹ אֲדָמָה, הַנּוֹגֵעַ בַּבָּשָׂר, טָמֵא. בָּאֲדָמָה, טָהוֹר. רַבִּי יְהוּדָה אוֹמֵר, אַף הַנּוֹגֵעַ בָּאֲדָמָה שֶׁכְּנֶגֶד הַבָּשָׂר, טָמֵא:

The egg of a creeping animal, in which the young animal is already developed, is clean, but when it has the smallest perforation it renders unclean. In respect to a mouse which is yet half flesh and half earth, 16 if the flesh is touched it renders unclean, but not if only the earth thereof had been touched. R. Jehudah saith, "Whoever touches the earth which immediately adjoins the fleshy part is also unclean."

Jastrow

Jastrow