ItlNG-OirSELS. 125 



is said to liannt tlie moutli of the Lewes river, near 'New- 

 haven ; and the Cornish chough builds, I know, all along 

 the chalky cliffs of the Sussex shore. 



I was greatly pleased to see little parties of ring-ousels 



downwards ; the same process in the cross-hill is spherical. The cavity in the 

 lower jaw, destined to receive tliis process, is a hollow circular cup. The 

 union of these two portions, thereforcj foims an articulation possessing the 

 universal motion and flexibility of the mechanical hall-and-socket joint. The 

 lower jaw is of great strength, the sides or plates elevated, with prominent 

 coronoid processes, to which, as well as to the whole outer sides of the plates, 

 the temporal muscle is attached ; and in a head of this bird, which had been 

 divested of all the soft parts, I found, on sliding the lower laterally upon the 

 upper, as performed by the bird, that, before the coronoid process is brought 

 into contact with the pterygoid, on its own side, the extreme points of the 

 mandibles were separated laterally to the extent I have already mentioned of 

 3-8ths of an inch. The temporal and pyramidal muscles on the right side of 

 the head (that being the side to which the lower jaw inclined,) were consider- 

 ably larger than those of the left, and indicated by their bulk the great lateral 

 power this bird is capable of exerting, to he hereafter noticed. The unusually 

 large size of the pterygoid muscles, on each side, was very conspicuous, the 

 space for them being obtained by the great distance to which the articulated 

 extremities of the lower jaw were removed ; and the food of the bird being 

 small seeds, rendered a narrow pharynx sufficient for the purpose of swallow- 

 ing. The muscles depressing the lower mandible are three in number, only 

 one of which, the greater pyramidal, is visible. This strong muscle covers 

 two other small ones, the triangular and square muscles, so called from their 

 particular shape. These three muscles, all of which have their origin in the 

 occipital portion of the cranium, are inserted by strong tendons on the under 

 and back of each extremity of the lower jaw, behind the centre of motion, and, 

 consequently, by their simultaneous contraction, raise the point to which they 

 are attached, and depress the anterior part of the mandible. The lower 

 portions of the ossa quadrata are pushed somewhat forwards by this compression, 

 assisted hy two small muscles ; one of these, a small flat muscle, arises from 

 the septum of the orbits, behind the small aperture observed in the septum, 

 and passes downwards to be inserted upon the projecting styloid process of the 

 OS quadratum. The second is -a. small pyramidal-shaped muscle, arising also 

 from the septum, anterior to the other muscle, and, passing downwards and 

 backwards, is inserted upon the omoid&um,, both by their contraction pulling 

 the OS quadratum forwards, and thus elevating the other mandible. The 

 depressors of the lower jaw, and the elevators of the upper, therefore, act 

 together to separate the mandibles. To close the mandibles, the temporal and 

 pterygoid muscles elevate the lower jaw, assisted by slender slips, which, 

 extending forwards to the superior maxillary hones, act in concert, by bringing 

 them down. When the lateral motion is required, the great pyramidal muscle 

 on the right side pulls the extremity of the lower jaw, to which it is attached, 

 backwards, the pterygoid muscles on the left side at the same time powerfully 

 assisting, by carrying that side of the lower jaw inwards." 



Mr. Yarrel next goes on to explain the use of the tongue. Their food is 



