382 R. S. Lull — Foot/prints of Stegomus Longipes. 



sideration, which was therefore provisionally placed in the order 

 Protorosauria of Seelej. A comparison was made however 

 between Batrachopus and Aetiosaurus, but those forms described 

 by Fraas lacked the proportions necessary to correlate the two 

 genera. 



In the Aetiosaur {Stegomus longipes), described by Emerson 

 and Loomis on p. 377 of this number, we find a form whose 

 stilted limbs and comparatively narrow body give it just the 

 proportions one would suppose Batrachopus to have, and a 

 careful comparison with the wealth of material contained in the 

 Hitchcock ichnological cabinet of Amherst College seems to 

 correlate it beyond doubt with the species Batrachopus graci- 

 lis E. Hitchcock, for the correspondence in size is exact. 



The genus Batrachopus contains three typical species, B. 

 deweyanus E. H., the type species, B. dispar Lull, and B. 

 gracilis E. H. the last presenting at least two varieties differing 

 from each other mainly in size, each being in this respect com- 

 paratively constant, though gradational specimens do occur. 

 Of these varieties the type specimen, the one here figured, 

 that described by Hitchcock,* is of the smaller phase, and 

 it is with this that Stegomus longipes agrees, while the larger 

 form is that described and figured in the author's memoir (loc. 

 cit., p. 484, fig. 3). These two forms are mainly from two local- 

 ities : the typical variety being seen most commonly on a ripple- 

 marked gray shale from the Horse Race near Gill, Massachu- 

 setts, the slabs being covered with tracks running in every 

 direction as though the creatures were gregarious in habits, as 

 the specimen of Aetiosaurus described by Fraasf would also 

 seem to indicate. 



The larger variety has its typical locality at the Lily Pond 

 quarry at Turners Falls, Massachusetts, which has yielded so 

 many of Hitchcock's types, and the specimens are for the most 

 part beautifully preserved impressions on a dark red shale, 

 which preserves detail with wonderful fidelity. 



Geographically Batrachopus gracilis ranges from Massachu- 

 setts through Connecticut, New Jersey and Pennsylvania, and 

 hence it is sufficiently numerous and widespread to be among 

 the species most likely to be preserved as fossils. 



If one may judge from relative size, it is possible that the 

 footprints of Sltegomus arcuatus Marshy are those to which the 

 name Bratrachopus dispar Lull has been given. 



It would seem therefore that the correct placing of Batrach- 

 opus would be not among the Protorosauria but in the sub- 

 order Aetiosauria of the order Parasuchia of Huxley. 



*Mem. Amer. Acad. Arts and Sci. (2), iii, p. 228, pi. 16, fig. 3, 4. 

 f Wiirttem. naturwiss. Jahres., xxxiii, l8?7. 

 X This Journal (4), ii, p. 59, pi. i. 



