Prof. Owen's Description of the Lepidosiren annectens. 357 



Tab. XXIV. 



Muscular System of the Lepidosiren annectens. 



Fig-. 1 . a. Dorso-lateral series of muscles. 



h. Ventro-lateral series of muscles. 



c. Levatores pinnce caudalis superiores. 



d. Levatores pinnce caudalis inferiores. 



e. Levator scapulae. 



f. Retractor scapulae. 



g. Temporalis. 



h. Biventer, seu apertor oris. 



i. Mylohyoideus, seu constrictor branchiarum. 



The temporalis is an extremely powerful muscle, arising from 

 the whole lateral part of the fronto-parietal bone, the median crest 

 of which is developed for the purpose of increasing the surface of 

 attachment, and consequently the bulk of the principal closer of 

 the jaws. Small muscles pass from the ascending process of the 

 upper maxillary to the under surface of the single intermaxillary 

 bone, which they depress, and thereby serve to infix the sharp and 

 slender intermaxillary teeth in the prey of the Lepidosiren. The 

 analogue of the biventer maxillae is a penniform muscle, and takes 

 its origin from the upper and outer surface of the tympanic bone : 

 it is inserted into the outer part of the lower jaw near the angle, 

 and opens the mouth. Small choanoid muscles are attached to 

 the base of the cartilage of each filamentary fin. 

 2. a. a. Fibro-gelatinous 'chorda dorsalis'. b. A portion of the central 

 gelatinous part removed, leaving the fibrous capsule to which 

 the ribs r. r. are attached. 



c. Bone representing the anchylosed anterior and posterior basi- 



sphenoid dnd basi-occipital bones. 



d. Pterygoid abutment, which is here a process of the superior maxil- 



lary arch. 



e. Cartilaginous pedicle and joint of the lower jaw, strengthened ex- 



ternally by the tympanic bone. 



