FROG: EXTERNAL FEATURES AND BODY- WALL 43 



processes of the vertebrae which represent the ribs, 

 and inserted into the under side of the suprascapula, 

 which it draws backwards, outwards, or inwards 

 according to the division which is contracted. 



d. Muscles inserted into the Hind-Limb. 



e.g. Gluteus, arising from the ilium and inserted into 

 the femur, which it rotates inwards. 



e. Muscles inserted into the Hip Girdle. 



e.g. Coccygeo-iliacus, arising from the urostyle and 

 inserted into the ilium, which it holds firm as a 

 fulcrum for the movements of the hind-limb. 



f. Muscles of the Backbone. 



e.g. Longissimus dorsi, a band running the whole 

 length of the back, divided by tendinous inter- 

 sections, which are attached to the transverse 

 processes, and inserted in front into the skull. It 

 straightens the back. 



B. Muscles of the Head. 



1. Muscles underneath the Head. 



e.g. Sternohyoid from hyoid to pectoral girdle. 



Geniohyoid from hyoid to chin. 



Hyoglossus from hyoid to tongue. 



Petrohyoid from hyoid to auditory capsule. 



Mylohyoid, submandibular, or submaxillaris, a sheet of 



muscle running from side to side of the lower jaw. 

 These muscles alter the position of the floor of the 

 mouth. 



2. Muscles of the Lower Jaw. 



e.g. Temporalis and masseler, arising from the skull and in- 

 serted into the lower jaw, which they raise. 



3. Muscles of the Eyeball. 



Rectus superior, r. inferior, r. externus (or lateralis), r. 



internus (or medialis), arising from the skull in the 



hinder part of the orbit and inserted into the eyeball. 

 Obliquus superior and 0. inferior, arising from the skull 



in the front part of the orbit and inserted into the 



eyeball. 

 These muscles will be more fully described in the chapter 

 on the dogfish. 



C. Muscles of the Fore-Limb. 



1. Muscles for the Upper Arm. 



e.g. Deltoideus, arising from the scapula and inserted into 

 the humerus. It raises the arm. 



2. Muscles for the Fore- Arm. 



Triceps brachii or anconeus, arising from the scapula and 

 humerus, and inserted into the upper end of the ulna. It 

 straightens the arm. 



There is no Biceps muscle in the arm of the frog. 



