466 



have found the same arrangement in the dog, dingo, and several other 



animals. 



1 7. The flexor brevis pollicis manus was also frequently severed into 

 two perfectly distinct muscles. The same state of perfect differentiation 

 I once saw in the extensor brevis digitorum pedis in the right foot of a 

 female subject 



18. The brachialis anticus I have found in one subject split nearly 

 through to its insertion, the cellular interspace between its heads ex- 

 tending down almost to the elbow. A distinct portion of this muscle I 

 found on one occasion arising from the intermuscular ridge of the hu- 

 merus. 



19. The pyriformis muscle I have seen in different degrees of fission, 

 sometimes the insertions of the two segments being apart; but more 

 commonly two muscular bellies have ended in a common tendon, and a 

 part (usually the peroneal portion) of the great sciatic nerve passed 

 backwards between them. 



20. Sometimes the costal fibres of the latissimus dorsi were separated 

 from the iliac portion of that muscle as far as the tendon. 



21. The cricothyroid I have once seen split into two parts. 



VI. Of our last series of varieties we have two subdivisions— the first 

 comprising those cases in which normal muscles are completely obsolete, 

 ami the second including those instances where partial suppression 

 occurs; to these might be added varieties by degeneration ; but it would 

 be perhaps more correct io exclude them entirely from our enumeration, 

 as they can have but little bearing upon questions of comparative myo- 

 logy, as being the results of influences acting upon parts which other- 

 wise would have been perfect in their embryonic and developed condi- 

 tions. Complete suppression I have found in cases of — 



1. Platisma myoides ; 2. zygomatic!, major and minor; 3. levator 

 palpebrse superioris, on both sides of a female subject, in whom there 

 was no sign of ptosis ; 4. pyramidalis nasi ; 5. trachelo-mastoid ; 6. ser- 

 ratus posticus superior, very rarely absent ; 7. serratus posticus inferior ; 

 8. sterno -thyroid ; 9. omo-hyoid, twice — in one instance on both sides, 

 and in the other a rudiment was visible on the left, while the muscle was 

 completely absent on the right ; 10. triangularis sterni ; 1 1. palmaris lon- 

 gus ; 1 2. lumbricales manus, and in one case lumbricales pedis, except 

 the one for the third toe ; 13. pyriformis ; 14. psoas parvus, so fre- 

 quently absent, that Theile considers it not to be a normal constituent 

 of the human body, although Meckel falls into the singular error of say- 

 ing that it is not often absent; 15. plantaris more frequently absent 

 than palmaris, in the proportion of three to two ; 16. gemellus superior, 

 as mentioned by Gantzer, and as we find in stenops; 17. gemellus in- 

 ferior, as occurs in the kangaroo and ornithorhynchus ; 18. peronasus 

 tertius ; 19. transversalis perinsei ; 20. transversus abdomini in one 

 instance; 21. palmaris brevis; 22. scalenus anticus; 23. the stylo- 

 hyoid muscle ; 24. transversalis pedis ; 25. tensor tarsi. 



Partial suppression I have found to take place regarding — 1. The 



