o/Bradypus t'ridactylus. 59 



eater Meckel describes two scapular heads, and one humeral. 

 Two scapular heads likewise exist in Dasypus — one a long 

 head proper, the other a more superficial and expanded origin ; 

 from these the dorsi-epitrochlear is quite distinct ; and thus, 

 with the two humeral origins, we have five extensor muscles 

 on the back of the arm. In the Orycterope there are four 

 heads, two humeral and two scapular (Galton). Three scapular 

 origins are described by Prof. Humphry. 



The anconeus externus is distinct and large ; the epitrochleo- 

 anconeus (Gruber*) is large and underlies the flexor carpi 

 ulnaris, and crosses over the ulnar nerve ; this muscle arises 

 from the inner condyle, and its fibres pass transversely out- 

 Avards to the olecranon process. It is present in the Orycterope 

 (Cuvier, Humphry, Galton), in the Tamandua (Rapp), in 

 Myrmecophaga juhata (Pouch et), Dasypus sexcinctus^ tricinctiis 

 (Gruber), M. didactyla (Gruber), Manis, Choloepus didactylus 

 (Galton), D. (Tatiisia) novemcinctus (Galton). 



The pronator teres is large, as in most of the Edentata, and 

 arises from the inner condyle of the humerus. It soon sepa- 

 rates into two portions near its insertion ; and these occupy the 

 lower half of the radius and the anterior surface of the wrist- 

 joint. In the Armadillo its insertion is also to the lower part 

 of the radius, occupying about one-half of that bone. It is 

 similar and undivided in the Anteater and Orycterope. The 

 median nerve is underneath it in all ; and there is no trace of a 

 coronoid head in any of these. (Journal of Anat. & Phys. 

 1867, p. 9.) 



Pronator quadratus is a small muscle occupying the lower 

 sixth of the forearm ; its fibres run dn their usual ulno-radial 

 course at an angle of about 60° with the shaft of the radius. 

 Meckel says that this muscle is smaller in the Ai than in any 

 other mammal, and that it occupies only one-eighth of the 

 forearm ; but this did not exactly describe the appearance in 

 om- specimen, for, though small, it was not quite so insigni- 

 ficant as the great German anatomist found it, as in our in- 

 stance it was at least as long as broad. I did not find a trace 

 of it in the Armadillo, as Galton and Meckel observe ; and it 

 seems likewise to be absent in Myrmecophaga didactyla (Mec- 

 kel). It exists, however, in M. juhata (Pouchet), M. tamandua 

 (Rapp), and Orycteropus, in which Prof. Humphry describes it 

 as small, and Mr. Galton as filling the whole interosseous 

 space of the forearm, as well as the anterior face of the radius 

 and ulna. 



Flexor carpi radialis is a small muscle, and passes from the 



* Memoires de TAcademie Imp6riale des Sciences de St. Petersbourg, 

 ser. 7. vol. x. p. o. 



