278 C. H. HUBST, PH.D. 



was relaxed, bring the feathers into some such position as that which 

 they occupy in the fossils known to us. These tendons and ligaments 

 may well have been very small, and the absence of any trace of them 

 in the fossils is not sufficient justification for our stating that they did 

 not exist. We must, therefore, remain in ignorance as to whether 

 Archceopteryx could or could not spread and close its tail. 



Though the feathers are small, their great number gives to the tail, 

 looked upon as an aeroplane, a very considerable surface, and this 

 surface is greatly increased by the development of a series of feathers, 

 which may for convenience be classed as rectrices, along the sides of 

 the hinder part of the trunk. So far as I can make out by means of 

 drawings that I have made to scale of the bird in the flying position, 

 these lateral rows of feathers constitute with the tail-feathers a con- 

 tinuous aeroplane, extending forwards as far as the posterior edge of 

 the extended wings. All those who have made drawings of the animal 

 "restored," so far as I know, ignore the existence of this lateral 

 aeroplane, and represent the lateral feathers of the tail-series as coming 

 to an end in the tail, and the London specimen certainly suggests that 

 this is the truth of the matter : the Berlin specimen, however, leaves 

 no room for doubt as to the accuracy of the account I have now given. 



Archceopteryx, unlike any other known bird, bore quills on its tibise. 

 These are not either remiges or rectrices — and, indeed, the lateral 

 aeroplane in front of the tail is not strictly made up of rectrices. In 

 the absence of a better name, I will call them tibial quills. These 

 appear to have lain in a single plane, which is the plane of flexion of 

 the leg, the plane in which femur, tibia, and metatarsals all lie when 

 the limb is bent; and they were apparently arranged in two series along 

 the surfaces corresponding to the anterior and posterior surfaces of the 

 human tibia, i.e., the extensor and flexor surfaces. The number of 

 them cannot be made out with certainty. The longest appear to have 

 measured a little over 30 mm. in length. How they were placed in 

 reference to the muscles I cannot say, and though they appear to have 

 lain in a single plane, they may perhaps — though I do not believe it — 

 have been "breeches," as they have been described. They extended 

 along the whole length of the tibia, and certain appearances in the 

 region between the left leg and the tail in the Berlin specimen suggest 

 that the flexor-series extended also to the region of the femur. 





