86 



Tedofpondyh' 



destitute of an anal fin, and their vertebvffi, when fully devel- 

 oped, ai'e strengthened by concentric layers of calcified tissae ; 

 they are hence named Tectospondyli (covered-vertebrae). The 

 " Sharks and Dog-Fishes " always exhibit an anal fin, and when 

 the vertebrae are strengthened, radiating plates predominate ovei- 

 concentric plates; they are thus known as AsTEuosPONnYLi 

 (star-vertebrje). It is impossible as yet to make any satisfac- 

 tory arrangement of the ancestors of these two sub-orders 

 which are destitute of vertebrae, or have them only incom- 

 pletely formed. 



Table-case, 

 No. 31. 



"Wall-case, 

 No. 3. 



Table-case, 

 No. 32. 



SuB-oRDKR I. —Tectospondyli. 



The Spinacida?, or spiny dog-fishes, of the present day are 

 supposed to be little-modified descendants of the early ancestoi'S 

 of the rays ; but they are scarcely known among fossils. Well- 

 preserved fishes which seem to belong to the existiaig genera 

 Acanthias and Centrophorus, are exhibited from the Upper Chalk 

 of Mount Lebanon. The Petalodontida^, of Carboniferous and 

 Permian age. may perhaps be related to the Spinacida?, but they 

 are only known by fragments, chiefly teeth. Petalodtis and 

 Foltjrhizodus are Lower Carboniferous, while Janassa is both 

 Carboniferous and Permian. The existing Squatinidse date 

 back to the Lower Kimmeridgian, fine examples of Squat ina 

 being known from the Lithographic Stone of Bavaria (Figs. 114, 

 115) . Detached teeth are exhibited from the English Cretaceous, 

 Eocene, and Pliocene Formations. The Pristiophoridffi are 

 insignificant as fossils, and the Pristidse ai'e represented 

 only by the Cretaceous Sderorhynchus and by fragments of 

 Prist is-\{]s.e " saws " from the Eocene and later deposits. 

 Sclerorhynchus at aims is a remarkable fish from the Upper 

 Chalk of Mount Lebanon, Avith the " saw " scarcely more 

 developed than that of a Pristioplwrus. Numerous Rhino- 

 batidiB, appai-ently identical with the existing Rhinobatiis, occur 

 well-preserved in the Lithographic Stone of Bavaria and 

 France, and in the Upper Cretaceous of Mount Lebanon. The 

 fine slab of Bhinohatus (Sjyatholatis) bugesiacns affixed to 

 the wall between Wall-cases Nos. 2 and 8, is particularly 

 worthy of examination. The Rajidae and Trygonida? are 

 also repi'esented by numerous fine specimens from the Ujiper 

 Chalk of Mount Lebanon, there being apparently Eaja itself 

 and a small extinct sting-ray named Gyclobatis. Torpedos 

 occur in the Upper Eocene of Monte Bolca, near Verona, but 

 are not represented in the Collection. 



The Carboniferous teeth warned Psammodus and Copodns may 

 belong to a family of devil-fishes, related to the modern 

 Myliobatida^, but their relationships are very iincertain. They 

 are always found detached, and a large series is exhibited from 



