CrossnpteryglL 



99 



scales and obfcusely-lobate paired fins. EhizoJopsis is represented 

 by small species in the Carboniferous, EMzodus and Strepsodus 

 by comparatively large species. A fine series of remains of 

 lihizodns Hihherti and R. oruatns, from the Lower Carboniferous 

 of Scotland, is exhibited in Wall-case Xo. 6. 



Wall-case 

 No. 6. 



-Osteokpis Tiuicrolepulnluf, \r. (resrnrrd by C. II .Pander) ; L. Old Red 

 sandsioiie, Scjtlaii.l. 



Table-casBj 

 No. 35. 



The CoelacanthidiB (hollow-spines) are tlie most remarkable Wall-case, 

 Crossopterygians, rano-ing almost unchansfed from the Lower ^°;,^' ^^^ 

 Devonian to the Upper Chalk. Their name refers to tlie cir- 

 cumstance that the spines of the backbone are only superficially 

 ossified and so appear bollow when fossilized. The head-bones 

 and opercular bones are much reduced, and the tail is produced 

 into a small terminal extension. The air-bladder is ossified. 

 The trunk is covered with thin, deeply overlapping scales. 



Fig. liO.—Utulina {Ilolo-pliagus) fjido, Egert. ; Lower Lias, Lyme Regis. 



'Coelacanthus is Carboniferous and Permian ; Undina (Fig. 140) 

 is Jurassic, and beautiful specimens are exhibited from the 

 Lower Lias of Lyme Regis ; Macropoma is Cretaceous, and 

 represented by the unique collection of Dr. Mantell besides 

 later acquisitions from the English Chalk. 



