386 DAVISON. [Vol. XI. 



muscles : thoracico-hyoideus, omo-humero-maxillaris, genio- 

 hyoideus, mylo-hyoideus, stylo-hyoideus, genio-glossus, cerato- 

 hyoideus externus, and trachealis arcuum. The thoracico- 

 hyoideus is a large muscle extending from the median extremity 

 of the cerato-branchial backwards until it is inseparably min- 

 gled with the rectus abdominis. Its fibres are interrupted by 

 several inscriptiones tendineae, which are present as far for- 

 ward as the gill slit. The omo-humero-maxillaris is well 

 developed, arising from the fascia ventralward of the fore limb, 

 and increasing in strength as it runs forward to its insertion 

 on the angle of the maxillary. The genio-hyoideus is a thin 

 band of muscle, arising from the symphysial region of the man- 

 dible, and is inserted in the fascial sheath of the thoracico- 

 hyoideus. The mylo-hyoideus forms a thin sheet of muscular 

 fibre extending transversely between the rami. The stylo- 

 hyoideus lies posterior to and deeper than the former muscle, 

 and extends from the cerato-branchial to the cerato-hyal and 

 hypohyal bones and basi-hyal cartilage. The genio-glossus 

 lies in the floor of the mouth parallel with the ramus connect- 

 ing it with the hypohyal. The cerato-hyoideus-externus lies 

 immediately beneath the stylo-hyoideus. The trachealis arcuum 

 is composed of a transverse band of fibres extending from the 

 fascia of the tracheal region to the tendon joining the summits 

 of the epibranchials. Its function I believe to have been the 

 retraction of these arches. Fischer, Duges, Humphry, 

 Schmidt, Goddard, and Van der Hoeven disagree to such an 

 extent upon the names of the muscles of the Amphibian head 

 that I have not adopted any one man's nomenclature, but have 

 retained the name which seemed most proper for the muscles 

 of Amphmma. 



Muscles of the Limbs. 



So far as I have been able to learn no one has yet attempted 

 to describe the muscles of AmpJiimna s limbs. The minute- 

 ness and massing together of the muscles render it a most 

 difficult undertaking. On the ventral aspect of the fore limb 

 are seen four muscles. The largest one, representing the 



