418 E. S. Lull — Life of the Connecticut Trias. 



Both vertebrates and invertebrates are thus represented. 

 Of the latter the actual fossils are impressions of at least two 

 species of shells, allied to the modern fresh-water Unios, a small 

 crustacean, and a single aquatic insect species, the last occur- 

 ring in profusion of numbers, and bearing the unique distinc- 

 tion of being the oldest true insect larva known. Some of the 

 trails are worm-like as though made by annelids, others show 

 serially repeated footmarks in pairs of fours or sixes or more, 

 indicating the presence of other arthropods than Monnolu- 

 coides, many of which were doubtless insects, others myria- 

 pods, perhaps spiders and scorpions, and fresh-water crusta- 

 ceans as well. Some of these are small and of wondrous 

 delicacy, others larger than the trails of any insects of fresh- 

 water crustaceans known, which must represent giants among 

 their race. 



The fishes, all of the old-fashioned armored sort, have been 

 alluded to as occurring in abundance from time to time in the 

 black shale bands, representing lake deposits with a luxuriant 

 growth of plants. 



The terrestrial vertebrate skeletons are all reptilian remains ; 

 three those of phytosaurs, remotely related to living crocodiles, 

 and, in one instance at least, economically equivalent to the 

 fish -eating gavials of the Far East. The others are all dino- 

 saurs of average size and representative kinds, neither the 

 largest nor the most specialized which lived during the time of 

 which we speak being known to us. Unfortunately, too, the 

 dinosaurian skeletons were those of contemporaries and, there- 

 fore, in themselves throw no direct light upon evolutionary 

 history. Of the five species four are so nearly related as to 

 be of one family and three of one genus, while the other rep- 

 resents a different race, which in its ultimate culmination was 

 far apart from the group for which the others stand, though 

 all were sanguinary devourers of flesh. 



The footprints represent two, possibly three, great classes of 

 terrestrial beings. Amphibia of salamandrine form were per- 

 haps present, and doubtless representatives of the more archaic 

 armored stegocephalians as well, though one cannot indicate 

 the track of either with assurance. Of the reptiles, the possi- 

 bilities of time and place would indicate lizards, turtles, and 

 dinosaurs among the more familiar forms, and these unques- 

 tionably were represented in the fauna, and among those less 

 known the Rhynchocephalia, phytosaurs, aetosaurs, and thero- 

 morphs are within the possibilities. 



Whether or not birds were present is still a mooted question. 

 The elder Hitchcock considered all of the bird-like tracks 

 unquestionably to have been of avian origin, but the discovery 

 of dinosaurian remains soon swung popular, if not scientific, 



