NO.1301. OSTEOLOGY OF HEMIBRANCHIATE FISHES-STARKS. 629 



The hypocoracoid is a very slender, widely forked bone. Its upper 

 fork is attached above the middle of the clavicle, inclosing a large 

 triangular space between. Its outer lower edge turns over slightly 

 and forms the slender ganoid line along the lower part of the side in 

 front of the pectoral. 



The actinosts are very small, semiquadrate, and without openings. 

 One and a half of them are attached to the hypocoracoid, two and a 

 half to the hypercoracoid. 



The Shoulokr Girdle of Aulostomus valentini. 



AULOSTOMID.K. 



The epiotocs are large, low, conical bones at each side of the supra- 

 occipital. Each articulates to the frontal anteriorly, to the exoccipital 



Fig 3 -Left shoulder girdle ok Aulostomus valentini from outer side. n. actinosts; cl 

 clavicle; h!/oc, HYPOCoRACoii,; In/pr. hypercoracoid; p, pectoral fin; pel. postclavicle, and 

 2)t, posttempokal. 



posteriorly, and to the pterotic at its outer edge. The pterotic forms 

 the posterior lateral angle of the cranium. It is anterior to the exoc- 

 cipitals, which form, with the basioccipital, a posterior projection. 

 The exoccipitals project downward on each side far below the condyle 

 of the basioccipital. They meet broadly above the foramen magnum. 



The post-temporal is not united with the cranium. It is a large 

 ganoid plate seen externally behind the head, above and anterior to 

 the triangular ganoid portion of the clavicle. It lies rather loosely 

 against the cranium, over, but scarcely in contact with, the pterotic 

 and epiotic. From its inner surface it sends a fork which rests rather 

 loosely behind the part of the exoccipital that projects below the 

 basioccipital. 



The supraclavicle is absent. 



The clavicle is a rather heavy triangular bone, as viewed from the 

 outside. The anterior edge which borders the branchial cavity is 



