1899.J THE MYOLOGY OF THE EDENTATA. 323 



or portions of the pectoral mass. Eegarding as we do this mass 

 and the pannicukis of the region as portions of the differentiated 

 lateral slieet of muscle carried out by the limb-bud, we believe 

 achselbogen to be a rudimentary condition represented in its 

 fullest dev^elopment by the presence of a muscular floor to the 

 axilla, and that in both these conditions we have to do with a 

 section of the sheet lying between the pectorals and the latissimus 

 dorsi. This arrangement has been noticed in Dasypus (22, 23, 2-1:), 

 Tatusia (25, 26), and GhJamydopliorus (27, 28). In the last- 

 named animal Macalister describes a special bundle of fibres I'ising 

 from the mammillary processes of the first two lumbar vertebra? 

 and gaining insertion into the posterior inferior angle of the scapula. 

 We can quite concur with his statement that this bundle is not 

 found in any other Edentate. 



Latissimo-olecranalis. — This muscle is always present in Eden- 

 tates, and is singularly well developed in many of them. In the 

 Bradiipodidce the muscle is not of great size ; in Bradypus it is 

 inserted into the internal supra -condylar ridge (1, 2, 4, 6), while in 

 Choloejnis it is attached to the arch of the large supra-condylar 

 foramen. In the My nnecophcujklcB the muscle is of fair size and 

 (in the specimen 0. 11 at the K. C. 8.) attached to the inner side of 

 the olecTanon. Pouchet (11.) speaks of an " accessoire interne " 

 arising from the infraspinous fossa in his specimen (12). This 

 may be a displaced latissimo-olecranahs, though the condition is 

 clearly abnormal, since it was neither found by Macalister nor hy 

 ourselves (11). In Tamandua (14) we found the muscle with its 

 usual attachments ; but Rapp (III.) found it rising from the scapula 

 close to the teres major, a condition whic-h nearly agrees with that 

 described by Pouchet as the " accessoire interne." In Cydothwus 

 the muscle has a more extended insertion than in the other Ant- 

 eaters ; it is attached to the forearm from the olecranon process to 

 the palmar fascia (17, IS, 19, 20). Humphry (IV.) says that from 

 its insertion the palmaris longus takes origin, this being one of 

 several instances of unusual continuity between muscles generally 

 separate one from another in other Orders. In the Dasypodidce. 

 the muscle is very large and often has further origins than that 

 which it obtains from the latissimus dorsi. In Dasypus (22) we 

 found it rising («) from the main insertion of the latissimus dorsi, 

 {h) from the dorsum scapulae, and (c) from that part of the 

 latissimus dorsi muscle which arises from the thoracic vertebrje. 

 The muscle covered the dorsal and internal aspects of the arm and 

 Avas folded round the triceps in such a way as to render that muscle 

 invisible until the latissimo-olecranalis was removed. The insertion 

 was into the olecranon and upper half of the subcutaneous margin 

 of the ulna. This is the maximum development of the muscle 

 so far met with by us in any mammal. Galton does not mention 

 any independent origin from the scapula in this animal (23), but 

 otherwise his description agrees with our own. Cuvier and 

 Laurillard (24) figure the same extensive insertion. In Taiusia 

 the muscle is very large, and in one specimen (25) obtains an extra 



