135 



my list I have the following additions :— -( 13) pronator quadratus in 

 four cases, disposed in various ways — either lying in two strata or divided 

 into two portions, an upper and a lower. In the left arm of a female, 

 examined November, 1866, the pronator was in three parts — one, a 

 small separated fascicle, the low est, arose tendinous from the front of the 

 ulna immediately above its articular extremity, and was inserted fleshy 

 into the lowest surface of the radius, to which it passed downwards and 

 outwards. The remaining part of the muscle was disposed in two 

 strata, the superficial of which arose from the fifth of the ulna, com- 

 mencing two-thirds of an inch above the styloid process ; its origin 

 was tendinous, and from it the fibres passed in a direction slightly 

 radiating to be inserted into a space of the radius a little wider than 

 usual : at the upper and inner side of the muscle the deeper lamina 

 of fibres came into view, and they were entirely exposed by reflecting 

 the superficial stratum ; they arose from the ulna, commencing a little 

 above the lower border of the superficial fibres, and extending rather 

 higher on the bone than the limit of origin of the former. These latter 

 are rather behind the limit of the interosseous membrane, a portion of 

 which intervenes between their layers. This specimen indicates the two 

 series of variations which I have found. When this muscle is disposed 

 in two strata, they generally are disposed with their tendinous and 

 fleshy parts alternate. Another forearm exhibited a trifid pronator, 

 one a narrow triangular band below tendinous at the ulna, and fleshy 

 at the radius ; the middle likewise triangular, but has its tendon and belly 

 in the opposite direction ; the superior, being quadrilateral, had. its fleshy 

 portion similar to the lowest part. A third specimen showed a small 

 pyriform fleshy belly, which originated from the lower end of the ulna, 

 crossed obliquely downwards to the end of the radius, where it ended 

 in a tendon, which was inserted into the aponeurotic structures over the 

 scaphoid, trapezium and trapezoid bone. This slip was nothing but an 

 extraordinary development of the lower border of the pronator, and its 

 nature and affinities have been before discussed. Varieties of the pro- 

 nator are not very frequent ; but they have been noticed by Meckel, 

 who has described it as double ("Anatomie," Jourdain and Breschet's 

 Transl. vol. ii. p. 179). Barton, of the Philadelphia Hospital, has 

 likewise described a peculiar condition of this muscle, in which it was 

 composed of two triangles — one with a radial base and an ulnar apex, 

 and the other with an ulnar base and a radial apex (Barton, quoted 

 in Horner's " Special Anatomy," vol. i. p. 426). 



(14.) The pronator radii teres I have seen cleft in one distinct in- 

 stance, which I have described with others in the " Journal of Anatomy," 

 vol. ii., No. 1. 



(15.) The specimen of cleft subscapularis has been recorded in the 

 same Journal, vol. i. p. 316. A similar instance I recorded and figured 

 in my former paper, "Proceedings Eoyal Irish Academy," vol. ix. plate 

 7a; (16) high differentiation in one instance occurred in the extensor 

 longus digitum pedis, and in the representative muscle of the forelimb. 

 (17) Of very common occurrence is a fission of the subcruraBus, which 



