416 Proceedings of the Royal Irish Academy. 



specimen I have found attacliecT above to the oblique processes of the 

 third, fourth, and fifth cervical vertebrae, and inserted below into the 

 middle third of upper border of clavicle. 



Rhombo-atloideus (ilaealister, 1866) ; splenius accessorius (Krause) ; 

 ndjutor splenii v. m. singularis splenius accessorius (Walther). — This 

 muscle passes from the spinous processes of the last cervical or first 

 dorsal vertebra — where it arises beneath the rhomboideus minor — 

 to the transverse process of the atlas. It has been found attached to 

 the sixth and seventh cervical spines, or to the seventh alone, or to 

 the first and second dorsal spines, or to the second and third. I have 

 found thi'ee examples in which the muscle arose from the last cervical 

 and first dorsal spines, and one in which it arose from the three upper 

 dorsal. In two cases the origin was fi'om the two upper dorsal vertebrae. 

 Mr. Wood found it three times in thirty- six subjects, and Krause gives 

 eight as its percentage of frequency. I have found it six times in. 

 seventy-five subjects. 



Atlanto-mastoicleus. — Arises from transverse process of atlas, and is 

 inserted into the posterior border of the mastoid process of the tempo- 

 ral bone. Krause makes its relative frequency to be thii'ty per cent, 

 of subjects examined ; this is much greater than what has occurred in 

 my experience, as I have found it but four times in thirty-three sub- 

 jects which were carefully examined for it. 



Rectus capitis anticus major, . . . minor. — Doubling of these 

 muscles I have pretty often observed, but have kept no account of the 

 relative frequency. 



Rectus capitis lateralis accessorius ("Winslow). — This muscle, a 

 doubling of the normal rectus capitis lateralis, I have found three 

 times in thirty-three subjects in which it was specially sought for. 



Pectoralis major. — The three parts of this muscle I have found 

 completely distinct in four instances. The clavicular, sternal, and 

 costal portions could easily be differentiated even down to their very 

 insertion into the humerus. In two cases I have seen an accessory 

 slip to the short head of the biceps taking origin from the lower border 

 of the tendon. In one case the tendon divided into two parts, between 

 which passed the long tendon of the biceps, one lamina going to either 

 lip of the bicipital groove. 



Pectoralis mcjor accessorius. — Arises from the costal cartilages, 

 fi'om the first or second to the sixth or seventh, and passes outwards 

 beneath the deep fibres of the pectoralis major to join the tendon of 

 insertion. It is but a complete differentiation of the costal portion of 

 the pectoralis major. 



Cliondro-epitroclilearis. — Of this muscle I have met with four speci- 

 mens. The attachments were the same in aU cases. The origin was 

 from the sixth costal cartilage, and the fibres were placed in close 

 apposition with the lower fibres of the pectoralis major. The inser- 

 tion was into the brachial aponeurosis at the lower fourth of the arm 

 on its inner aspect — one sending a slight tendinous slip down to the 

 epitrochlea. So that the muscle in all these cases better deserved the 

 name of chondro-fascialis. 



