Chapter 15

Birds bend their legs in the same way as quadrupeds. For their natural construction is broadly speaking nearly the same. That is, in birds the wings are a substitute for the forelegs; and so they are bent¹ in the same way as the forelegs of a quadruped, since when they move to progress the natural beginning of change is from the wings (as in quadrupeds from the forelegs). Flight in fact is their appropriate movement. And so if the wings be cut off a bird can neither stand still nor go forwards.

Again, the bird though a biped is not erect², and has the forward parts of the body lighter³ than the hind⁴, and so it is necessary (or at least preferable for the standing⁵ posture) to have the thigh⁶ so placed below the body as it actually is, I mean growing towards the back. If then it must have this situation the flexion of the leg must be backwards⁷, as in the hind legs of quadrupeds. The reasons are the same as those given in the case of viviparous quadrupeds.

If now we survey generally birds and winged insects, and animals which swim in a watery⁸ medium, all I mean that make their progress in water by dint⁹ of organs of movement, it is not difficult to see that it is better to have the attachment¹⁰ of the parts in question oblique¹¹ to the frame, exactly as in fact we see it to be both in birds and insects. And this same arrangement obtains also among fishes. Among birds the wings are attached obliquely¹²; so are the fins¹³ in water animals, and the feather-like wings of insects. In this way they divide the air or water most quickly and with most force and so effect their movement. For the hinder parts in this way would follow forwards as they are carried along in the yielding medium, fish in the water, birds in the air.

Of oviparous quadrupeds all those that live in holes, like crocodiles, lizards¹⁴, spotted¹⁵ lizards, freshwater tortoises, and turtles, have their legs attached obliquely as their whole body sprawls¹⁶ over the ground, and bend them obliquely. The reason is that this is useful for ease in creeping into holes, and for sitting upon their eggs and guarding them. And as they are splayed outwards¹⁷ they must of necessity tuck in their thighs¹⁸ and put them under them in order to achieve the lifting of the whole body. In view of this they cannot bend them otherwise than outwards.

1 bent   

n.爱好，癖好；adj.弯的；决心的，一心的

参考例句：

• He was fully bent upon the project.他一心扑在这项计划上。
• We bent over backward to help them.我们尽了最大努力帮助他们。

2 erect   

n./v.树立，建立，使竖立；adj.直立的，垂直的

参考例句：

• She held her head erect and her back straight.她昂着头，把背挺得笔直。
• Soldiers are trained to stand erect.士兵们训练站得笔直。

3 lighter   

n.打火机，点火器；驳船；v.用驳船运送；light的比较级

参考例句：

• The portrait was touched up so as to make it lighter.这张画经过润色，色调明朗了一些。
• The lighter works off the car battery.引燃器利用汽车蓄电池打火。

4 hind   

adj.后面的，后部的

参考例句：

• The animal is able to stand up on its hind limbs.这种动物能够用后肢站立。
• Don't hind her in her studies.不要在学业上扯她后腿。

5 standing   

n.持续，地位；adj.永久的，不动的，直立的，不流动的

参考例句：

• After the earthquake only a few houses were left standing.地震过后只有几幢房屋还立着。
• They're standing out against any change in the law.他们坚决反对对法律做任何修改。

6 thigh   

n.大腿；股骨

参考例句：

• He is suffering from a strained thigh muscle.他的大腿肌肉拉伤了，疼得很。
• The thigh bone is connected to the hip bone.股骨连着髋骨。

7 backwards   

adv.往回地，向原处，倒，相反，前后倒置地

参考例句：

• He turned on the light and began to pace backwards and forwards.他打开电灯并开始走来走去。
• All the girls fell over backwards to get the party ready.姑娘们迫不及待地为聚会做准备。

8 watery   

adj.有水的，水汪汪的；湿的，湿润的

参考例句：

• In his watery eyes there is an expression of distrust.他那含泪的眼睛流露出惊惶失措的神情。
• Her eyes became watery because of the smoke.因为烟熏，她的双眼变得泪汪汪的。

9 dint   

n.由于，靠；凹坑

参考例句：

• He succeeded by dint of hard work.他靠苦干获得成功。
• He reached the top by dint of great effort.他费了很大的劲终于爬到了顶。

10 attachment   

n.附属物，附件；依恋；依附

参考例句：

• She has a great attachment to her sister.她十分依恋她的姐姐。
• She's on attachment to the Ministry of Defense.她现在隶属于国防部。

11 oblique   

adj.斜的，倾斜的，无诚意的，不坦率的

参考例句：

• He made oblique references to her lack of experience.他拐弯抹角地说她缺乏经验。
• She gave an oblique look to one side.她向旁边斜看了一眼。

12 obliquely   

adv.斜； 倾斜； 间接； 不光明正大

参考例句：

• From the gateway two paths led obliquely across the court. 从门口那儿，有两条小路斜越过院子。 来自辞典例句
• He was receding obliquely with a curious hurrying gait. 他歪着身子，古怪而急促地迈着步子，往后退去。 来自辞典例句

13 fins   

[医]散热片；鱼鳍；飞边；鸭掌

参考例句：

• The level of TNF-α positively correlated with BMI,FPG,HbA1C,TG,FINS and IRI,but not with SBP and DBP. TNF-α水平与BMI、FPG、HbA1C、TG、FINS和IRI呈显著正相关，与SBP、DBP无相关。 来自互联网
• Fins are a feature specific to fish. 鱼鳍是鱼类特有的特征。 来自辞典例句

14 lizards   

n.蜥蜴( lizard的名词复数 )

参考例句：

• Nothing lives in Pompeii except crickets and beetles and lizards. 在庞培城里除了蟋蟀、甲壳虫和蜥蜴外，没有别的生物。 来自辞典例句
• Can lizards reproduce their tails? 蜥蜴的尾巴断了以后能再生吗？ 来自辞典例句

15 spotted   

adj.有斑点的，斑纹的，弄污了的

参考例句：

• The milkman selected the spotted cows,from among a herd of two hundred.牛奶商从一群200头牛中选出有斑点的牛。
• Sam's shop stocks short spotted socks.山姆的商店屯积了有斑点的短袜。

16 sprawls   

n.（城市）杂乱无序拓展的地区( sprawl的名词复数 )；随意扩展；蔓延物v.伸开四肢坐[躺]( sprawl的第三人称单数 )；蔓延；杂乱无序地拓展；四肢伸展坐着（或躺着）

参考例句：

• The city sprawls out to the west, north and south. 该市向西、北、南方不规则地扩张[延伸]。 来自互联网
• Explanation: Our magnificent Milky Way Galaxy sprawls across this ambitious all-sky panorama. 说明：我们宏伟的银河系蜿蜒穿过这幅高企图心之全天影像。 来自互联网

17 outwards   

adj.外面的，公开的，向外的；adv.向外；n.外形

参考例句：

• Does this door open inwards or outwards?这门朝里开还是朝外开？
• In lapping up a fur,they always put the inner side outwards.卷毛皮时，他们总是让内层朝外。

18 thighs   

n.股，大腿( thigh的名词复数 )；食用的鸡（等的）腿

参考例句：

• He's gone to London for skin grafts on his thighs. 他去伦敦做大腿植皮手术了。 来自《简明英汉词典》
• The water came up to the fisherman's thighs. 水没到了渔夫的大腿。 来自《简明英汉词典》