300 Mr. J. Wood on some Varieties in Human Myology, [June 16, 



redundancy more frequent or more developed on the right side ; those 

 from deficiency on the left. 



Variations hy simple reduplication. 



The following muscles have been observed double, or in two distinct 

 layers : — Pectoralis, major and minor ; gluteus maximus ; soleus ; pyra- 

 midalis abdominis ; pyriformis j subclavius. 



Variations by deficiency. 



The following have been seen totally deficient :— Psoas parvus ; palmaris 

 longus ; superior and inferior gemellus ; extensor minimi digiti j pyra- 

 midalis abdominis ; pyriformis ; peronseus tertius ; extensor primi inter- 

 nodii pollicis ; trapezius ; plantaris and palmaris brevis (rarely) . 



The following have been seen partly deficient : — Trapezius ; omo-hyoid ; 

 sterno-hyoid ; serratus magnus ; internal oblique and transversalis abdo- 

 minis ; soleus. 



Other varieties observed (all illustrated by drawings). 



1 . An offset from the platysma myoides below the ear, reaching from 

 the trapezius and occipito-frontalis to the parotid fascia and risorius San- 

 torini (homologue of the panniculus carnosus). 



2. Extensive origin of omo-hyoid from the clavicle, in addition to its 

 scapular attachment. 



3. Double omo-hyoid, the upper one digastric, the lower uninterrupted by 

 tendon, and attached to base of coracoid process. Not before recorded. 



4. Levator claviculce. — Clavio- or acromio-trachelian, observed in two 

 subjects, on both sides, arising with the levator angidi scapulcB from the 

 third and fourth cervical transverse processes, and inserted into the outer 

 third of the clavicle under the trapezius. Found in all the Ape- tribe. 



5. Costo-fascialis. — A broad muscular band arising from the first rib 

 and cartilage, outside the sterno-thyroid, and lost in the fascia of the upper 

 half of the neck. Not before described. 



6. A double anterior belly to the digastric muscle, with complete decus- 

 sation across the median line. The latter peculiarity not before recorded. 



7. Sternalis brutorum. — Rectus sternalisYel thoracicus connected above 

 with a prolongation downwards of the sternal tendon of the sterno-mastoid, 

 muscular fibres spreading out below over the sternal and epigastric apo- 

 neurosis, and attached to the xiphoid and fifth, sixth, and seventh costal 

 cartilages. 



8. Double subclavius. — The lower fibres distinct from upper, with ce- 

 .phalic vein passing between them, and attached to the coracoid process. 



9. Broad slips from pectoralis major and latissimus dorsi, passing 

 across axillary vessels and nerves, and attached, low down the arm, to the 

 aponeurosis inserted into the inner condyle of humerus and olecranon pro- 

 cess. These slips are highly developed in some of the anthropoid Apes ; 



