A treatise on zoology . i^° - -».^- ->..•--1 Diagrammatic restoration of Lanarkia spiaosa, Traq. Dorsal view with the tail twisted toshow the heterocercal caudal fin. The eyes appear near the anterior border. (After Traquair, Trails. Roij. Soe. KiHii.) tubercles or ridges, A large median dorsal plate is situated above, tworostral plates at the anterior edge ; a large median ventral plate occursbelow, with a median mental in front. The mouth was situated inthe transverse slit between the rostrals and the mental ; and a cloacalaperture seems to have been placed behind the ventral. Anterior an
A treatise on zoology . i^° - -».^- ->..•--1 Diagrammatic restoration of Lanarkia spiaosa, Traq. Dorsal view with the tail twisted toshow the heterocercal caudal fin. The eyes appear near the anterior border. (After Traquair, Trails. Roij. Soe. KiHii.) tubercles or ridges, A large median dorsal plate is situated above, tworostral plates at the anterior edge ; a large median ventral plate occursbelow, with a median mental in front. The mouth was situated inthe transverse slit between the rostrals and the mental ; and a cloacalaperture seems to have been placed behind the ventral. Anterior and. Fig. 108. Diagrammatic restoration of Thelodus scoticus, Traq. Dorsal view with the tail twisted toshow the caudal and dorsal fins. The eyes are shown near the anterior border. (After Traquair, Trans. Ru/. Soc. Edin.) posterior ventro-lateral plates occur, also a pair of lateral plates arepierced by a hole, which probably represents the orbit. The eyes were,then, rather ventral than dorsal, and far apart. The lateral flaps, theexpanded edge of the body, are enclosed in long postero-lateral spaces between the large plates are covered with a mosaic of smallerpolygonal pl^es, which are continued on to the tail and caudal fin, wherethey acquire* the shape of imbricating scales diminishing in size behind. P TERA SPIDOMORPHI The dorsal and the ventral edge of the tail are strengthened with amedian series of stout fulcral scales (Traquair [467-8]}. Drepanaspis, Schliiter; Lower Devonian, Prussia. Family Psammosteidae. Incompletely known fossils, representedby large convex plates,
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishe, booksubjectzoology
