52 Prof. A. Macallster on the Myology 



with great care and accuracy ; so that we are in a position to 

 appreciate the special myological characters of the entire order. 

 The specimen of Three-toed Sloth was in good condition, small; 

 and, as many of its epiphyses seemed to be still cartilaginous, 

 it was evidently a young animal. 



On removing the skin from the back and side, very few 

 platysmal fibres were visible ; indeed the only portions of the 

 panniculus carnosus present were a few scattered weak fasciculi 

 at its lower or abdominal end, and a very few sparse bundles 

 in the neck, much weaker than I have found in Dasypus sex- 

 cinctus. 



The trapezius was a thin muscle, rather smaller than usual, 

 arising from all the cervical spines with the exception of the 

 first, and from the upper six of the dorsal spines ; it was in- 

 serted into the scapular spine for its whole length, and into the 

 acromion process. I could trace no fibres into the rudimental 

 clavicle, although such an arrangement is described by Meckel 

 both in this animal and in the Anteater ; similarly, I found no 

 clavicular fibres in the Dasyjyus sexcinctuSj and in this respect 

 agree with the observations of Mr. Galton, who says that in 

 Ovycterojnis also no clavicular fibres exist. This muscle in the 

 Ai is undivided, as also in Orycteropus ; but in the Armadillo 

 it is split distinctly into upper and lower portions. Meckel in 

 his description assigns to this muscle a much more limited 

 range of origin than that which I have found. 



The rhomboideus is small and sino-le : it arises from the 

 last cervical and the upper three dorsal spines. Its insertion 

 is normal. There is no trace of an occipital slip ; but in Da- 

 sypus I found a true occipito-scapular slip largely developed. 

 The same condition occurs in Orycteropus '^ but, with the ex- 

 ception of a slight differentiation in direction, it is not separa- 

 ble into true major and minor portions (Galton). In the Two- 

 toed Anteater its arrangement, according to Meckel, is similar 

 to that in the Ai'. 



I found no levator claviculai or trachelo-acromial (omo- 

 atlantic of Prof. Haughton) ; it is described as existing in the 

 Orycterope under the name of cervico-humei-al (Humphry), 

 acromio-basilar (Galton) ; and it is likewise present in the 

 Armadillo, and inserted into the clavicle. 



The levator scapulas is not distinct from the serratus mag- 

 nus, and hence Meckel describes it as non-existent ; but as we 

 recognize any cervical prolongation of the serratus magnus as 

 a levator scapulas (for in truth the latter in its most perfect 

 condition is nothing else than a neck prolongation of the 

 former), so it is probably more correct to say that the levator 

 scapulai segment of the serratus arises from all the cervical 



