Mr. F. O. Ward on the Motion of the Ann. 411 



immediately beneath the great coal-field, is incorrect, it be- 

 ing only " an alternating series lying above the great body of 

 carboniferous limestone." This objection is obvious, if what 

 I have termed the transition limestone at the base of this 

 series be secomlary, "carboniferous;" and if it can be proved, 

 in the district I have imperfectly described, to " repose con- 

 formably on the extensive formation of old red sandstone." 



On this head I wish to be understood, not as insisting on 

 the infallibility of my own individual sentiments, but as de- 

 sirous of apprising geologists of the grounds on which those 

 views were founded. At the same time I am not quite pre- 

 pared to admit, with Mr. Weaver, that the whole of the coal 

 deposits in Pennsylvania, belong to one great carboniferous 

 order, and that the fact " is fully established by Professor 

 Eaton." (p. 131.) 



A vast deal of investigation remains yet to be entered into 

 before these debateable points can be adjusted. There is 

 good prospect of some of them being shortly elucidated by the 

 geological surveys simultaneously going on in the States of 

 NewYork, Pennsylvania, Maryland and Virginia. 

 Philadelphia, Sept. 23, 1836. 



LXXVIII. Physiological Remarks on certain Mtiscles of the 



Upper Extremity, especially on the Pectoralis Major. Bt/ 



F. O. Wakd, Esq., King's College, London.* 

 [With a Plate.] 

 T^HERE is a remarkable fold in the tendon of the pectoralis 

 major, which, though described by all anatomists, has 

 never yet, I believe, been explained. The muscle consists of 

 two portions, one smaller and upper, arising from the clavicle, 

 and passing downward and outward ; the other larger and 

 lower, arising from the sternum and ribs, and having a ge- 

 neral direction upward and outward. The fibres of the muscle 

 thus converging towards each other, terminate in a flat tendon 

 several inches wide, which is attached to the upper part of the 

 humerus. 



Instead, however, of having the usual simple insertion re- 

 presented in Plate IV. fig. 1, the lower part of this tendon is 

 folded up, behind the upper portion, so that the margin B 

 appears above the margin A, as represented in fig. 2. 



As it is an axiom in physiology that every arrangement is 

 to be accounted for, this peculiar twist has given rise to se- 

 veral speculations. Some suppose it designed merely to di- 

 minish the extent of the insertion. Otiiers believe it to have 



* Read before the Royal Society Jiinel Hth, 1836 : ami now coninuinicaled 

 by tiie Author. 



3 C 2 



