. College collection of palaeontology. REPTILIA. 53 No. 79. [237] Placodus gigas, Agassiz. Skull (cast). This reptile (formerly called a fish) was a Plesiosaurian, ac- cording to Owen, breathing the air like Cetaceans. No part, save the head has been found. The cranium *is as broad as long, the figure viewed from above being that of a right-angled triangle with the corners rounded off. No other number of the class has such wide tem- poral fossae and strong zygomatic arches; the lower jaw, moreover, presents an excessive development of the coronoid process. These developments, for great size an
. College collection of palaeontology. REPTILIA. 53 No. 79. [237] Placodus gigas, Agassiz. Skull (cast). This reptile (formerly called a fish) was a Plesiosaurian, ac- cording to Owen, breathing the air like Cetaceans. No part, save the head has been found. The cranium *is as broad as long, the figure viewed from above being that of a right-angled triangle with the corners rounded off. No other number of the class has such wide tem- poral fossae and strong zygomatic arches; the lower jaw, moreover, presents an excessive development of the coronoid process. These developments, for great size and power of action of the biting and grinding muscles, relate to a most extraordinary form and size of the teeth, which resemble paving stones, and were evidently adapted to crack and bruise shells and crusts of marine Inverte- brates. The palatal teeth, three on each side, are of large size; the maxillary teeth, four in number, are much smaller; thepremaxillary teeth, three in each ramus, are elongated and conical. The palatal are relatively larger than the teeth of any known animal, living or fossil. All these teeth are implanted in distinct sockets. This skull was found in the Muschelkalk (Trias) at Laineck, Bavaria, and belongs to the University Museum of Munich. Size, ORDER MOSASAURIA (Pythonomorpha). This order includes tlie huge elongated creatures typified by the Mosasau7'us^ and formerly classed with the Lacertilia. They were eel-like in form and movements, and probably the most elongated of reptiles, some attaining a length of perhaps eighty feet. The feet were modified to form slender paddles. Small scales probably covered the body. The head was pointed, flat, with eyes nearly vertical. Four rows of rootless teeth were borne in the upper jaw, and each half of the lower jaw had a unique articulation near the middle whereby the creature was enabled to swallow large prey, for while, like serpents, the rami were loosely joined in front by ligaments there was not as
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