ART. 15 ANATOMY OF THE EARED AND EARLESS SEALS HOWELL 51 



of the basioccipital, laterad of the rectus major. Miller found that 

 in Arctocefhahis origin was also from the axis. 



MUSCLES OF THE TRUNK 



Muscles of the thorax. — M. pannkulus carnosus (figs. 15, 18) waa 

 inseparable from the platysma. In the Zaioplms the fibers of the 

 latter extended directly ventrad over the scapula, and of the pan- 

 niculus, converged progressively from the dorsal fascia toward the 

 axilla, clear to the root of the tail. In the extended specimen the 

 ventral border of this muscle passed over the hip, and therefore the 

 knee, with a slight ventral sag, joined the dorsal border of the 

 pectoralis, from which it was separable with difficulty, and inserted 

 into the connective tissue distad of the medial elbow. In the Phoca 

 a very different state of affairs obtained. There was no converging 

 of the fibers to the axilla, but origin was somewhat laterad of the 

 middorsal line and all fibers were uniformly directed ventro-craniad 

 at an angle from the vertical of about 35°, covering the knee and 

 extending almost to the base of the tail, in which vicinity the line 

 of origin extended somewhat more dorsad. Insertion of the portion 

 over the scapula was onto the fascia of the middle forearm, and of 

 the remainder upon the fascia of the ventral surface slightly laterad 

 of the midventral line. 



Miller found the true panniculus very similar in P. vituUna but 

 failed to indicate the degree of convergence of the fibers toward the 

 axilla — a most fundamental point. The platysmal part of this 

 sheet he divided in an unnatural manner, terming the sphincter colli 

 profundus the pectoral panniculus, and the like. Similarly, Murie 

 without a doubt confused his dissection of the panniculus of 

 Ev/metopias^ and not only illustrated the true panniculus as extend- 

 ing in several different directions, due possibly to the "set" posi- 

 tion of his specimen, but the parts of the facial musculature which 

 extend over the neck (platysma, spincters colli superficialis and 

 profundus) are shown in incorrect relationship. 



M. pectoralis (figs. 9, 10, 18, 19, 20, 22) in the Zalophus was imper- 

 fectly separable into three parts. The superficial sheet occurred as a 

 pars anticus, arising midventrad from as far craniad as the pre- 

 sternal tip and caudad practically to the fifth costal cartilage ; and a 

 pars posticus, arising midventrad from 50 mm. caudad of pars anticus 

 to the xiphoid cartilage. Both of these divisions united and were 

 inserted upon the tough fascia covering the distal palmar aspect of 

 the forearm continuous with the fibrous sheet of tissue immediately 

 beneath the skin of the palm. Muscle fibers ceased about at the wrist. 

 The pars profundus had origin extending from the presternal tip to 

 the xiphoid and converged to a tough aponeurotic insertion along 

 the deltoid ridge of the humerus and the slight ridge extending there- 



