Sentence:  If true, there is something peculiarly interesting in these periodical visitations—or, I should, perhaps, rather say migrations—of mice, for I was informed that these <WSD>muscine</WSD> armies come from the interior, or from that direction, towards the sea, which they boldly enter, and are consequently drowned and their bodies cast on the shore "by thousands." 
Meaning of the word marked with <WSD> tags:  Murine; of, pertaining to, resembling, or being a mouse.