STRUCTURE OF FOSSIL BONE. 71 



understood, may prove of service in the arts 'and advance 

 the mechanical powers of man. Comparisons with the same 

 bones in birds of similar flight and configuration of the 

 wing are highly useful in elucidating this subject. Take, 

 for instance, such birds as the ring-dotterel, turnstone, 

 dunlin, pigmy curlew^, little stint, and other birds of that 

 description, whose mode of flight is so similar that I will 

 defy the most practised sportsman to distinguish one from 

 the other by its flight. Now if we examine a portion of the 

 ulna, taken from the same part of the bone in any one or 

 all of these birds, we shall at once observe a similar and 

 singular correspondence in the disposition of the Haversian 

 tubes. Examine next the ulna of the greensand piper, a 

 bird whose wing is broader than, and not so pointed as, the 

 above mentioned, and whose flight is easily recognised from 

 its congeners by the sportsman, and you will notice an 

 entirely dififerent arrangement of the Haversian tubes, which 

 are reticulated in every direction, while in the rest they 

 observe longitudinal directions ; what conclusion can we 

 arrive at, but that these tubes are arranged in accordance 

 with the flight of these birds. The starling, the raven, the 

 jay, &c., have all fine and numerously reticulated tubes, and 

 the secondary quills of all these birds are well developed. 

 In the fowl they are very powerful, and the ulna contains 

 numerous and fine tubes ; in the owls the same ; in the 

 hawks the Haversian tubes are large and much reticulated, 

 and are easily recognised from those of other birds. It 

 seems, therefore, possible, from the microscopic structure of 

 the bone of a bird, to di^dne the shape of its wing and the 

 character of its flight, there being a perfect correspondence 

 the one Avith the other, just as a perfect knowledge of the 

 femur will inform us whether a bird coidd swim, or only run, 

 or walked ; and this may be done even in a fragment of a 

 bone, after we have acquainted ourselves with the general 

 principles by very numerous and exact observations. 



In the coracoid, for instance, the ordinary disposition of 

 the Haversian tubes would be longitudinal, braced more or 

 less, because that would be the best arrangement to resist the 

 powerful action of the pectoral muscles. In the gannet, as 

 has been shown, a circidar arrangement is preferable, but 

 this is apparently an exception, and connected with the pecu- 

 liar habits of the bird. The ulna of the razor-bill and guil- 

 lemot is more reticulated than would primarily be expected 

 in the wdng of a bird where the secondary quills are so very 

 weak; but then it must be considered that those birds use 

 their wings much more like fins when under vv^ater than as 



