52 Prof. A. Macallster on the Myoloyy 



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

 appreciate the special mjological 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 hbrcs 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 Dasi/pus sex- 

 cinctus. 



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

 arising from all the cervical spines with the exception of the 

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

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

 acroniion 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 Basi/jjus sexcinctus^ and in this respect 

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

 Orycterojms^ also no clavicular fibres exist. This muscle in the 

 Ai is undivided, as also in Orycterojjus ; 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 single ; 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 Orycferojms- 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 claviculas or trachelo-acromial (omo- 

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

 Or^xterope under the name of cervico-humeral (Humplny), 

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

 Armadillo, and inserted into the clavicle. 



Tlie levator scapuh\3 is not distinct from the serratus mag- 

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

 recognize auy cervical prolongation of the serratus magnus as 

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

 condition is notiiing else than a neck prolongation of the 

 former), so it is prol)a1)ly more correct to say that the levator 

 acapulai segment of the serratus arises from all the cervical 



