392 H. R. POLLARD, 



traces of a division into 2 or 3 portions. Its origin is from the der- 

 mal clavicle and interclaviclc. Thence the fibres converge and are at- 

 tached by o tendons to the end of the ceratohyal. The internal tendon 

 is stouter than the other two and in it is formed a strong tendon bone 

 which remains in macerated skeletons. The median tendon is slight. 

 The outer, though not so powerful as the internal is yet of considerable 

 size and serves mainly for the attachment of that portion of the muscle 

 which springs from the dermal clavicle. 



Curiously enough where the muscle is joined by connective tissue 

 to its fellow of the opposite side a forked tendon bone occurs. 



From the posterior portion of the coracohyoideus passes a long 

 tendon to the lower end of the 1st ceratobranchial. The innervation 

 of the above muscle is from the last cranial, really the 2nd spinal 

 nerve. 



The Branchiomandibularis s. Gciiiohjoideus is a long paired muscle. 

 It arises from the posterior end of the 1st basibranchial and proceeds 

 to the symphysis of the jaw. It has a greater extent vertically than 

 horizontally. 



Innervation is from the anterior prolongation of the conjoined two 

 last cranial (1st and 2nd spinal) nerves. The nerve reaches the muscle 

 on its ventral surface near its posterior end. 



To the system of Coracoarcuales belongs a muscle (fig. 6) which 

 arises from the last ceratobranchial and runs horizontally forward af- 

 fixing itself, by tendons to the lower ends of the 2nd and 1st cerato- 

 branchials. It is supplied by the united 1st and 2nd spinal nerves. 

 The branches to it leave the common nerve before the latter reaches the 

 geniohyoid. Possibly here also belongs a flat muscle of small size 

 which takes its origin from the hinder edge of the last ceratobranchial. 

 It loses itself in the skin near the anterior edge of the dermal clavicle. 

 Its innervation was not discovered. 



Comparison with other animals. 



In comparing the muscles of PoJypterus with those of Selachii it 

 must be remembered that Polypterus though exceedingly primitive is 

 yet a much ossified form. The muscles do not take their origin as in 

 the latter largely from fasciae but directly from bones either dermal or 

 preformed in cartilage. However certain portions of the Constrictor 

 superficialis, the "oberflächliche Ringmusculatur" of Vetter in the 

 mandibular and hyoid regions retain a primitiveness comparable with 

 that of Heptanchus. The Levator maxillae superioris of which the 



