OSTEOLOG Y OF BER YCOID FISHES— STA nhS. 1 3 



VERTKRHAL COLUMN AND APPENDAGES OF VERTUAI. FINS. 



Abdouiiiuil verteljnv 11 + caudal l."3 + hypural = 27. The atlas is 

 irregularly convex to conform to the occipital condyle. The upper 

 half is separated from the lower by a transverse ridofe, under the 

 middle of which is a slioht depression. The sixth vertebra bears the 

 first pair of parapophyses. The posterior parapophyses are connected 

 with their fellows of the opposite side ])y a bridge of bone, forming a 

 hwmal canal beneath. The first two vertebne bear only internmscular 

 rays. Each anterior rib is longitudinally widened above into a thin 

 plate. The posterior ones are widened transversely, the last pair 

 being extremely wide and forming wing-like processes at each side of 

 the first interhaemal spine. The intermusculars extend posterior to 

 the abdominal cavity. The interspinous rays of the spinous dorsal 

 coincide in number with the vertebral spines. Those of the soft dor- 

 sal and anal exceed them about two to one. The first interhpemal is 

 exceedingh" long and stout. It is formed by the fusing of three spines. 

 There are two auxiliary interneurals anterior to the spine-bearing 

 ones. The spines of the last two vertebrge assist the hypural in sup- 

 porting the caudal fin. The two vertebra? immediately in front of 

 these have the spines above and below flattened into plates. 



MYRIPRISTIS OCCIDENTALIS Gill. 



The cranium differs from that of Ilolocentrus in having the mucous 

 channels better developed and the bones not so thick and solid. The 

 posterior part of the cranium does not turn vertically downward at a 

 right angle with the top. The f rontals are not so large and do not 

 project over the parietals so nuich. The epiotic is not covered by the 

 parietal. The depression for the reception of the premaxillary process 

 is small and scarceh" extends between the frontals. The condition 

 of the anterior opening to the l)rain case is as in Jlolocentnis. The 

 alisphenoids are joined at the median line, and the orbitosphenoids 

 are fused into a single V-shaped plate. The ethmoid does not project 

 backward between the prefrontals, which are in contact l)ehind. The 

 olfactory foramen is through the prefrontal, rather than between it 

 and the ethmoid. The auditor}^ bulla does not extend back tul)e like 

 and open in a round hole, ])ut the entire side of the bulla is open. 

 The open space is surrounded by the same bones that it is in Jlolovcit- 

 triis. The air bladder sends lateral processes forward in the same way. 

 covering the opening. The rest of the skeleton is essentialU' as in 

 Holocentrua. 



