SCIENCE. 



[N. S. Vol. XV. No. S67- 



Seeley would ascribe to ancestral, funda- 

 mental impressions, and not to adaptation. 

 The present writer believes that the elonga- 

 tion of the wing finger, the progressive weak- 

 ening of the middle fingers and the peculiar 

 shape of the first finger are all purely adap- 

 tive, together with the shape of the humerus, 

 the peculiar form of the sternum, the anchy- 

 losis of bones, the shortening of tail and con- 

 comitant increase in length of the sacrum, 

 the diminution and loss of the fibula, the loss 

 of teeth, retreat of the nostrils, etc. The 

 bone in the lizard commonly called the 

 squamosal extends to, or nearly to, the brain 

 surface in the mosasaurs. If the determina- 

 tion of the bone be right, this character loses 

 its value as an avian index in the ptero- 

 dactyls ; if wrong, there is the same possibility 

 in the pterodactyls. Dimorphodon had the fifth 

 toe peculiarly modified for the sustentation 

 of the patagial membrane. What good reason 

 then has Professor Seeley for supposing that 

 this specialization was lost in later forms; 

 that the membrane was restricted to the sides 

 of the body only? The rudimentary fifth toe 

 in Ornithostoma was divergent. What use 

 had it unless that of Dimorphodon? In bats 

 the membrane extends to the ankle and over 

 the tail. It is reasonable to suppose that such 

 were its relations in all the pterodactyls, the 

 later as well as the earlier. 



Especially does the writer disagree with 

 Professor Seeley in his opinion that the quad- 

 rupedal position of the body in ambulation 

 was a normal one. He doubts very much 

 whether the peculiar articulation of the 

 humerus would permit such a position of the 

 bones in some of the pterodactyls. And what 

 use were the loosely attached middle fingers 

 of some pterodactyls as ambulatory organs ? 

 In a specimen of Oi-nithostoma recently ac- 

 quired by the University of Kansas, the 

 small fingers are in position, from which it 

 is evident that they could not have been 

 brought to the surface of the ground in a 

 state of pronation. Nor does it seem reason- 

 able that the animals walked upon the 

 knuckles of the fifth fingers. In those ani- 

 mals in which the body is carried more or 

 less erect, as in birds and dinosaurs, there 



occurs elongation of both sacrum and ilium. 

 In the early pterodactyls there were three or 

 four sacral vertebraj; in Nyctodactylus, one of 

 the latest, there were six true sacral vertebrae- 

 and one coossified lumbar. It thus would 

 seem that some or all pterodactyls walked 

 erect when upon the ground, with the 

 knees probably much flexed. The pelvis of 

 Nyctodactylus, with an expanse of out- 

 stretched wings of fully eight feet was less, 

 than seven eighths of an inch in diameter at- 

 the brim, and not three fourths of an inch at 

 the outlet. The heads of the femora in the- 

 largest species measuring twenty feet in ex- 

 panse were less than two and a half inches 

 apart. If the legs were knock-kneed, as seems- 

 probable, both of the feet in such animals- 

 would have rested upon a space smaller than 

 one's hand. In the posture I have indicated, 

 with the body erect, the wing metacarpal 

 bones would have rested upon the ground at 

 the sides. 



The eggs of Nyctodactylus could not have- 

 been three fourths of an inch in diameter, and 

 of Ornithostoma not over two inches. How 

 big would the young have been recently 

 hatched from such eggs? Were they cared 

 for by their parents after birth? Did the: 

 pterodactyls build nests? 



S. W. WiLLISTON. 

 PAPERS ON ENGINEERING. 



The Proceedings of the Royal Society, just- 

 issued (Vol. XVI., Part II., Lond., Nov., 

 1901), contain a number of papers of pecu- 

 liar interest in the field of applied science and 

 engineering. 



The opening article is by Lord Eayleigh, oni 

 'Flight.' In this paper it is stated that the- 

 main problem in fiight is that of the aero- 

 plane, as in the case of the kite. But the kite> 

 is anchored and at rest relatively to the earth;, 

 while the aeronaut, the aviator, whether- 

 human or other, is adrift. No bird can main- 

 tain itself in motion in a uniform wind-cur- 

 rent without active exertion, any more than: 

 in an atmosphere at rest. Soaring is thus evi- 

 dently the outcome of utilization of internal 

 movements of the atmosphere surrounding the- 

 bird. The albatross presumably takes advan- 



