196 INTESTINAL STRUCTURE OF ICHTHYOSAURUS. 
in the modern voracious tribes of Sharks and 
Dog-fish.* 
As the peculiar voracity of all these animals 
required the stomach to be both large and long, 
there would remain but little space for the 
smaller viscera ; these are therefore reduced, as 
we have seen, nearly to the state of a flattened 
tube, coiled like a corkscrew around itself; 
their bulk is thus materially diminished, whilst 
the amount of absorbing surface remains almost 
the same, as if they had been circular. Had a 
large expansion of intestines been superadded 
to the enormous stomach and lungs of the 
Ichthyosaurus, the consequent enlargement of 
the body would have diminished the power of 
progressive motion, to the great detriment of an 
* Paley, in his chapter on mechanical compensations in the 
structure of animals, mentions a contrivance similar to that 
which we attribute to the Ichthyosaurus, as existing in a species 
of Shark, (the Alopecias, Squalus Vulpes, or Sea Fox). *' In 
this animal, he says, the intestine is straight from one end to the 
other : but, in this straight, and consequently short intestine, is 
a winding, cork-screw, spiral passage, through which the food, 
not without several circumvolutions, and in fact by a long route, 
is conducted to its exit. Here the shortness of the gut is com- 
pensated by the obliquity of the perforation." 
Dr. Fitton has called my attention to a passage in Lord 
King's Life of Locke, 4°. p. 166, 167, from which it appears 
that the importance of a spiral disposition within the intestinal 
canal, which he observed in many preparations in the collection 
of anatomy at Leyden, was duly appreciated by that profound 
philosopher. 
