360 MESSRS. GARROD AND DARWIN ON AN OSTRICH [Mar. 5, 



muscles of the abdominal wall would favour the idea of its corre- 

 sponding to the marsupial bone of the Kangaroo and its allies ; and 

 if that is the case, the whole of the anterior prolongation of the 

 Ostrich's pubis would correspond to the small ridge of bone on 

 either side of the superior margin of the symphysis pubis in the 

 Mammalia. 



The obturator interims also arises from the superficial surface of 

 this bone and its cartilage, as well as from the adjacent surface of 

 the ischium and from the pubis, extending so far forward that the 

 muscles of the opposite sides are only separated from one auother by 

 an inch or so at the symphysis pubis. 



Mr. Macalister, in his description of the myology of this bird, has 

 omitted a few of the muscles, some of which from the head will be 

 described, together with those of the leg, which Mr. Frank Darwin 

 has allowed me to introduce in this communication, from his notes 

 and the dissection of that limb in this individual specimen. 



Pterygoid. — From the inferior surface of the posterior part of the 

 palate-bone, and from the process of bone which connects it with 

 the main portion of it, this is fibrous — also from the whole of the 

 inferior surface of the pterygoid bone, extending inwards almost to 

 the basisphenoidal rostrum. 



The fibres are all directed backwards, and are inserted in two 

 ways : — the outer, and some of those from the palatine longitudinal 

 process, into the anterior surface of the transverse ridge at the 

 angle of the mandible, which posteriorly receives the insertion of 

 the digastric muscle ; the inner, and others from the palate-bone, into 

 a fibrous band which runs from the side of the median Eustachian aper- 

 ture and its cartilaginous continuation to the prominent ridge behind 

 and internal to the condyloid articular surface for the mandible, 

 thus forming an arch under which run the arteries and veins to the 

 head. 



This second portion of the muscle acts partly as an opener of the 

 Eustachian aperture, partly as a retractor of the slightly movable 

 pterygoid and palatine bones. 



Quadrato-mandibular. — From the whole of the longitudinal ridge 

 which forms the superior internal portion of the quadrate bone, and 

 from the surface of the bone external to it. The fibres are directed 

 outwards and downwards to be inserted into the inner surface of the 

 mandible, in front of the articulation, not extending to the inferior 

 margin, nor forwards further than the optic foramen. 



Quadrato-cranial. — From the back of the orbit, below and behind 

 the origin of the recti muscles and the exit of the nerve, from a 

 surface bounded above by a semicircular line, and extending down 

 in the space between the orbit and the quadrate bone. The fibres 

 are directed outwards to the corresponding, internal surface of the 

 quadrate bone, a slight ridge separating the superior ones from those 

 of the quadrato-mandibular. 



Gastrocnemius consists of two enormous masses of muscle blend- 

 ing together at their origins round the proximal end of the tibia, and 

 separating lower down into the gastrocnemius anticus, which laps 



