Royal Physical Society. 395 



oesophagus. On opening the swimming-bladder, it is seen to 

 be divided by a septum down the middle, which reaches from 

 its hinder extremity to the posterior margin of the body of the 

 fused vertebrae, where it ends in a free margin, in which the 

 pneumatic duct commences. The orifice between the anterior 

 and posterior division of the bladder, on each side of the sep- 

 tum, is only large enough to admit a probe. Four or five 

 rings of muscular fibre encircle at intervals each half of the 

 bladder posteriorly, projecting into it. 



The kidneys are but loosely connected with the abdominal 

 wall, and are dilated at their anterior extremities, which fit in 

 on each side of the constriction of the swimming-bladder. 



The urinary bladder is very largely developed, and is 

 thrown into numerous loculi. 



The testes and ovaries were empty in the specimens exa- 

 mined ; the testes were long and slender, — the ovaries short 

 and thick. 



Explanation of Plates. 

 Plate XX. 



Fig. 1. View from above of the bones of the head and the modified vertebrae. 

 2. View from below of the same. 



These two figures, and Plate II., Fig. 1, are marked with the same 

 series of letters and numbers — a supra-occipital bone — b ex-occipital 

 — c par-occipital — d basi-occipital — e mastoid — / great frontal — g 

 post- frontal — h ali-sphenoid — zbasi-sphenoid — h orbito-sphenoid — I 

 inter-orbital plate — m pre-frontal — n nasal bone — o vomer — ^inter- 

 maxillary — q supra-maxillary — r palate bone — s, t, u, v, pterygo-ty- 

 panic range, viz., s pterygoid, t hypo-tympanic, u epi-tympanic, 

 wsympletic — w opercular — oc inter-opercular bone — y supra-tempo- 

 ral cartilage — z infra-orbital range — a' dental piece of the lower jaw 

 — b' articular piece. 1. Transverse process of the second vertebra 

 (springfederfortsatz) — 2. Stem process — 3. Malleus — 4. Stapes — 5. 

 Neurapophysis of first vertebra — 6. Thread-like process of third 

 vertebra — 7. Body of first vertebra — 8. Body of second vertebra — 9. 

 Dorsal arch of second and third vertebra conjoined — 10. Transverse 

 processes of third vertebra — 11, 12. Spinous and transverse pro- 

 cesses of fourth vertebra — 13. Transverse process of fifth vertebra 

 — 14. Posterior articular process — 15. Scapula, the ligament joining 

 it to the basi-occipital being represented by a dotted line — /3. The 

 outlet of the Y-shaped canal, in which the aorta commences — y 

 lateral opening of the same— 2 olfactory foramen of the pre-frontal 

 bone. 



Fig. 3. Vertical section of the modified vertebrae, showing the division of the 



