o/" Bradypus tridactylus. 57 



Icejyus^ Dasypvs, Orycterojnis, and the Anteatcrs, The teres 

 major is very large and quite separate from the latissimus 

 dorsi, as it is in the Orycterope and Armadillo, not connected 

 to it as in the Great Anteater (Pouchet) or the Myrmecophaga 

 tamandua (Rapp). 



Coraco-hrachialis is small, and inserted into the upper 

 fourth or perhaps nearly the upper third of the humerus ; it is 

 undivided, and represents, according to Mr. Wood, the middle 

 rather than the short coraco-brachial muscle. The long form 

 occurs in the Orycterope (Humphry) ; in one specimen of this 

 animal, however, Galton describes a rudiment of the short 

 form : it is present also, in its long variety, in Myvmecophacja 

 jubata and tamandua ; the middle variety represents it in CJio- 

 Icepus didactylus. In the two above-mentioned Anteaters, 

 Messrs. Galton and Pouchet describe fibres from the root of 

 the rudimental coracoid inserted into the outer part of the 

 inner tuberosity. This condition is described by Mr. Galton 

 as occurring also in Macropus rujicollis and giganteus'^ and I 

 remarked it in a Wallaby and also in the shoulder of Glohio- 

 cephalus svineval (Proc. Zool. Soc. 1867, p. 481). In the 

 Armadillo both the short and long forms exist, as Mr. Galton 

 correctly describes. 



The biceps is a double muscle, and may be regarded as 

 consisting of a humeral and a scapular portion. The more 

 superficial or humeral arises from the anterior surface of the 

 humerus internal to the deltoid, but unconnected with that 

 muscle ; its origin extends for about one-half of the anterior 

 surface of the bone, and it overlaps the scapular head ; this 

 muscle passes downwards perfectly separate from the scapular 

 biceps, and is inserted into the tubercle of the radius. It 

 is accurately described by Meckel ; but in his case an 

 accessory head was received from the deltoid — a condition of 

 which I could not find a trace. This humeral head to the arm- 

 biceps does not exist in the Armadillo, Anteater, or Oryc- 

 terope ; but it is a common anomaly in human anatomy, oc- 

 curring, according to Theile, once in every eight subjects 

 (Encyclopedie Anatomique, vol. iii. p. 217) — a proportion which 

 I found to exist in the dissecting-room of the Royal College of 

 Surgeons, Ireland, during the session 1866-67 (Proc. Royal 

 Irish Acad. 1867). The accessory deltoid head described 

 by Meckel has its counterpart in another anomaly described 

 by me in the same paper — the fifth variety of the biceps 

 therein recorded, in which the biceps arose by a fleshy tongue 

 from the deltoid, and did not possess a long head : this, as we 

 shall presently see, is a close approach to the " Sloth " con- 

 dition. A coracoid and humeral biceps exists in Vespertilio 



