218 EXTINCT MONSTERS 
indicates that its wings were “rudimentary,” and quite useless 
either for flying or swimming (see Fig. 81). Modern penguins 
use their wings with great effect while swimming under water, 
but the Hesperornis was compensated for the want of wings by its 
broad tail, which was much expanded horizontally, and doubtless 
served as an organ of propulsion in diving. (The tail in our 
restoration is too small.) 
The brain was diminutive, and very like that of a reptile. It 
is impossible, in the absence of feathers, to say exactly what 
appearance the skin of this bird presented, but in the restoration, 
Plate XXXIV., our artist has to some extent taken a modern diver 
as his model. The skeleton of this bird presents several interesting 
points of resemblance with reptiles; but it will not be necessary 
to enter into anatomical details here. The remains were dis- 
covered by Professor Marsh, in certain marine Cretaceous strata 
along the eastern slope of the Rocky Mountains, which have 
also yielded mosasauroid reptiles, Pliosaurs, and Pterodactyls. — 
The valuable specimens on which Professor Marsh’s descriptions 
are based were not procured without considerable trouble and 
hardship. His exploring parties in the plains of Kansas and 
Colorado suffered, at one time, from extreme heat, causing 
sunstroke and fever, by which the guides and explorers alike 
were weakened and discouraged; at other times, from extreme 
cold, to say nothing of the danger from hostile Indians. But 
fortunately, the latter enemies to science were kept in check by 
escorts of soldiers. 
Hesperornis, as we have seen, was an admirable diver; while 
the long neck, with its capabilities of rapid flexure, and the long 
slender jaws armed with sharp recurved teeth, formed together a 
perfect instrument for the capture and retention of the most agile 
fish. As the lower jaws were united in front only by cartilage, as 
