飞鼠

The Classic of Northern Mountains: two hundred li northeast is Mount Tianchi. No grass or trees on the summit; much patterned stone. A beast lives there, shaped like a hare with a rat's head, which flies with its back. Its name is Feishu. "Flies with its back." Those four characters are the strangest part of the entry and also the truest. Take the animal first. China has flying squirrels — the true gliding squirrels — with about thirteen species, from the groove-toothed flying squirrel of the northeast to the brown flying squirrel of the south. Wide distribution. They do not fly. They glide. A membrane between the fore and hind limbs, the patagium, spreads into a thin aerofoil; the animal launches from a high canopy, covers tens or even a hundred metres, and lands on another tree. The attachment points matter. The membrane begins at the sides of the neck and runs along the flanks to the hind limbs and the base of the tail. Now picture it: dusk, poor light, a flying squirrel launching. Limbs spread, membrane taut. Seen from below, or from the side — what do you actually see? A spread sheet of membrane, joined along the back, wrapping the whole body into a flattened shape. A small head in front, a tail behind, and one continuous surface between. "Flies with its back." It looks exactly as though the thing on its back is doing the flying. And "shaped like a hare with a rat's head" — a flying squirrel perched on a branch, hunched into a ball, round-backed, short forelimbs, long hindlimbs, small round ears, does read as a small rabbit. But the face is pointed, the eyes large and black. A rat's face. So every feature in the record is accurate, and the order is the order of observation: first the perched whole (like a hare), then the face (like a rat), then the launch (flies with its back). The ancients had no anatomy. They did not know the membrane attaches at the wrist. They saw something spread open on the back. Now Mount Tianchi. The name has a well-known counterpart in northern Shanxi: the Tianchi lakes of Ningwu, in the Guancen range, at over seventeen hundred metres — a rare group of alpine lakes in north China. And the Guancen mountains still have groove-toothed flying squirrels. "No grass or trees on the summit, much patterned stone." The main peak, Luya Shan, is granite: bare rock and scree. So the location is probably the Guancen range in northern Shanxi. Now the picture completes. Dusk, a high northern mountain, bare rock, a lake, a few old trees at the shore. A flying squirrel drops from the canopy, spreads its membrane, and crosses the water without a sound, landing on the far bank. A hunter saw it. He had no word for gliding. He had "fly." And things that fly either have wings, or — like this one — have something that opens out of the back. He wrote it down: shaped like a hare, head like a rat, flies with its back. Two thousand years later we call it Trogopterus xanthipes, the complex-toothed flying squirrel. Its dried droppings are a Chinese medicine, wulingzhi, used to move blood and stop pain. In the Shanhaijing it has fourteen characters.

"บินด้วยหลัง" — สี่คำนี้คือส่วนที่แปลกที่สุดและจริงที่สุด ที่จริงคือกระรอกบิน จีนมีราว 13 ชนิด มันไม่บิน แต่ร่อน มีแผ่นหนังระหว่างขาหน้าและขาหลัง ตอนพลบค่ำ เห็นมันกางออก แผ่นหนังเชื่อมไปตามแนวหลัง ทั้งตัวแบนราบ หัวเล็กข้างหน้า หางข้างหลัง ตรงกลางเป็นแผ่นเดียว — ดูเหมือน "หลัง" ต่างหากที่บิน "รูปเหมือนกระต่าย หัวหนู" ก็ตรง: ตอนเกาะกิ่งมันขดกลมเหมือนกระต่าย แต่หน้าแหลม ตาดำโต เหมือนหนู เขาถียนฉือ = น่าจะเป็นเทือกเขากวานเฉิน มณฑลซานซี ซึ่งยังมีกระรอกบินชนิดนี้อยู่

"Terbang dengan punggungnya" — empat perkataan paling pelik dan paling tepat. Sebenarnya ini tupai terbang. China ada kira-kira 13 spesies. Ia tidak terbang, ia meluncur. Ada selaput antara kaki depan dan belakang. Waktu senja, selaput terbuka, menyambung sepanjang belakang, badan jadi rata. Kepala kecil di depan, ekor di belakang, tengahnya satu keping — nampak macam "belakang" itulah yang terbang. "Bentuk arnab, kepala tikus" pun tepat: masa bertenggek ia bergulung bulat macam arnab, tetapi muka tajam, mata hitam besar macam tikus. Gunung Tianchi mungkin banjaran Guancen di Shanxi utara, yang masih ada tupai terbang ini.

"Bay bằng lưng" — bốn chữ lạ nhất và cũng thật nhất. Thực ra là sóc bay. Trung Quốc có khoảng 13 loài. Nó không bay, nó lượn. Có màng da giữa chi trước và chi sau. Lúc hoàng hôn, màng xòe ra, nối dọc theo lưng, cả thân dẹt lại. Đầu nhỏ phía trước, đuôi phía sau, giữa là một tấm liền — trông như thể "cái lưng" mới là thứ đang bay. "Hình thỏ, đầu chuột" cũng đúng: khi đậu nó cuộn tròn như thỏ, nhưng mặt nhọn, mắt đen to như chuột. Núi Thiên Trì có lẽ là dãy Quản Sầm, bắc Sơn Tây, nơi vẫn còn loài sóc bay này.

"Terbang dengan punggungnya" — empat kata paling aneh dan paling tepat. Sebenarnya ini tupai terbang. Tiongkok punya sekitar 13 spesies. Ia tidak terbang, ia meluncur. Ada selaput antara kaki depan dan belakang. Saat senja, selaput terbuka, menyambung sepanjang punggung, tubuh jadi rata. Kepala kecil di depan, ekor di belakang, tengahnya satu lembar — tampak seperti "punggung" itulah yang terbang. "Bentuk kelinci, kepala tikus" juga tepat: saat bertengger ia menggulung bulat seperti kelinci, tetapi wajah tajam, mata hitam besar seperti tikus. Gunung Tianchi mungkin pegunungan Guancen di Shanxi utara, yang masih punya tupai terbang ini.