1868.] Mr. J. Wood on Variations in Human Myology. 491 



brium sterni opposite the second rib, and had no connexion with the sterno- 

 mastoid. It formed a slender muscular belly, A\ inches long by f of an 

 inch wide, and ended upon the sheath of the rectus opposite the sixth rib- 

 cartilage. 



This muscle has been found by the author in 7 out of 1 75 subjects, 

 > in which it has been carefully looked for. This is 4 per cent. Five 

 of the instances were in males, and 2 in females. In the males it was 

 found, in 1 on both sides, in 3 on the right side, and in 1 on the left side 

 only. In the females it was found in both instances on the right side only. 



Professor Turner fixes the frequency of its occurrence, from observations 

 upon 650 subjects, at about 3 per cent. He found it 9 times on both 

 sides, 5 times on the right, and twice on the left side only ; while in 5 

 more it was sino-le, and crossed the median line (Journ. of Anat. and Phys. 

 No. 2. May 1867, pp. 247, 248). Professor W. Gruber found it in 5 out 

 of 95 subjects, in 3 on both sides, once on the right, and once on the left 

 side only (Mem. de I'Acad. Imp. de St. Petersbourg, L. iii. 1860). 



Thirty-two columns of the Table are occupied by the remaining muscles 

 of the Arm. This is six more than those of last year ; the additional lines 

 of variation being made up by the stemo -scapular, anconeus epitro- 

 chlearis, extensor carpi intermedins, ext. pollicis et indicis, and ext. medii 

 digiti (which have been found so frequently as to require separation from 

 the muscles with which they are most closely connected), and the pronator 

 radii teres. 



9. Pectoralis major. — In the male (No. 2) and the female (No. 25) a 

 detached outlying slip was found on both sides at the lower border of this 

 muscle, arising from the epigastric aponeurosis covering the rectus 

 muscle, and inserted, separately from the rest of the pectoralis muscular 

 fibres, upon the deep surface of the upper fibres of the tendon of insertion. 

 In the male the slip was small on one side, and arose opposite to the sixth 

 rib-cartilage ; but on the other side large, and reaching as low as the seventh 

 rib. The author looks upon the above abnormality as the homologue of 

 the portion ventrale'^ of Cuvier and Laurillard's plates, constituting, in 

 most Mammalia, a large and separate portion of the pectoral group of 

 muscles. It is also homologous with the costo-humeraV of Professor 

 Huxley, and the chondro-epitrochlear of Duvernoy. Meckel describes it 

 as remarkably distinct in the Bats, drawing the wings powerfully down 

 and inwards (Anat. Comp. vol. vi. p. 206). Zenker describes it as the 

 '* hracMo- abdominal " muscle in the Batrachian reptiles, in whom it is 

 frequently continuous with the rectus abdominis (Batrachomyologia. 

 Jense, 1826, p. 39). 



In the male (No. 13) was developed, on the left side only, a very large 

 and well-marked example of the muscle described by the author as the 



chondro-coracoid.'' It is placed in the Table among the sundries. It 

 consisted of a separate muscle arising by two digitations, the upper from 

 the sixth rib, and the lower from the epigastric aponeurosis covering the 



