OCR Text |
Show 1906.] SYSTEM OF CERTAIN SPECIES OF ANURA. 1 0 1 1 rotria it originated in one specimen on botli sides of the body in the aorta, just behind the origin of the subclavia, while 011 the left side there was an additional vessel from between the subclavia and the occipito-vertebralis. I11 another individual of the same species it arose on both sides from the base of the occipito-vertebralis. In R. catesbiana it originated between the subclavia and the occipito-vertebralis. It divided 011 the oesophagus, and the main portion ran as a rather large vessel for a considerable way down the right side of the stomach, supplying a large portion of the cardiac region, over which it formed a close network. A branch of this network could easily be traced to the right lung, where it formed an anastomosis with branches of the pulmonary artery. Further back, its ramifications united with those of the ramus sinister of the A. codiaca. The point is not without interest as showing how, ultimately, as one may conceive, through the medium of such anastomoses a distinct vessel might arise in a purely secondary manner running either from the aesophcigea or the codiaca directly to the lung. A. subclavia.-The branches of this artery distributed to the pectoral girdle are liable to much variation in number, structure, and distribution. I am inclined to think that a careful examination of a large number of individuals is still needed to establish a satisfactory type of arrangement for the Anura. Two figures are appended showing their arrangement on both sides of the body in two individuals of R. temporaries which were injected together for the purpose (text-figs. 143, 144, p. 1012). Here, before the radial artery was given off, there were five (in one case four) arteries striking out at irregular intervals into the pectoral girdle, roughly with an anterior and posterior alternation. Retaining so far as possible the nomenclature of Gaupp :- (1 ) The A. thoracica superior, arising from near the occipito-vertebralis, took, in one of these two individuals, the usual course upwards and forwards, supplying the Mm. intertransversarius capitis superior and levator anguli scapulae 011 both sides of the body. In the other individual, the artery went 011 one side to the M. transverso-scapvlaris minor, and 011 the other side entirely backwards to the M. obliquus internus. (2) The A. thoracico-abdominalis went in three cases almost entirely to the M. obliquus internus; in the fourth case to the M. transverso-scapularis m ajor. (3) The A . coraco-clavicularis, perhaps the most constant member of the subclavian system, passed mainly in all cases through the coracoid foramen to the M. pectoralis sterncdis, a branch being given in two cases to the M. inter scapular is. (4) This, the largest branch, appeared in all four cases to be a combination of the Aa, dorsalis scapulae posterior and dorsalis scapulae anterior of Gaupp. In three cases a branch went to the ]\[. pectoralis abdominalis, but 011 all four sides one or more conspicuous branches ran to the skin of the upper arm or that of the |