February 12, 1904.] 



SCIENCE. 



255 



ordinal name Parasuchia. Though Hux- 

 ley's view has received quite general ac- 

 ceptance, several paleontologists, notablj^ 

 Marsh, Baur and E. Fraas, have observed 

 certain resemblances to Sphenodon and 

 the. dinosaiirs. The present studies of 

 the group, based chiefly upon extensive 

 material recently discovered in Germany 

 and in North America, have cleared up 

 most of the doubtful points of the skeletal 

 morphology, and it may be said that, save 

 for the carpus and tarsus, the phytosaurian 

 skeleton is now pretty well known. Nearly 

 all the newly discovered structures indicate 

 that the affinity to crocodiles is much more 

 remote than Huxley supposed, and certain 

 characters of the skull and atlas alone pre- 

 clude the possibility that these forms were 

 ancestral to crocodilia. The strong general 

 resemblance between the two groups is 

 chiefly superficial or parallel adaptation to 

 similar habit and environment. 



The relationship of phytosaurs to car- 

 nivorous dinosaurs, on the contrary, is ob- 

 scured by the adaptive or secondary differ- 

 ences correlated with bipedal habit in the 

 latter animals; but careful comparison of 

 the skeletons shows that the relationship 

 in this case is scarcely more remote than 

 the relationship with crocodiles. The 

 group which imdoubtedly stands nearest 

 the phytosaurs comprises the small ar- 

 mored Aetosauria; in fact, the phytosaurs 

 are chiefly distinguished from these animals 

 by the prenarial elongation of the snout. 

 For this reason it seems best to place the 

 two groups as suborders within a single 

 order, to designate which Huxley's sub- 

 ordinal name Parasuchia may be taken in 

 a more inclusive sense and raised to ordinal 

 value. The derivation of these Parasuchia 

 from Rhynchocephalian ancestors scarcely 

 admits of doubt; they might be briefly de- 

 scribed as Rhynchocephalia M'hich have ac- 

 quired strongly bicipital ribs, thecodont 

 dentition and a dermal armature. 



Evidence was also adduced to show ge- 

 netic affinity between Phytosauria and Ich- 

 thyosauria. Many structures, especially in 

 the skull and limb girdles, indicate deriva- 

 tion of both from a common ancestor at no 

 very remote period. 



On the Position of the Bones of the Fore- 

 arm in the Opisthocoelia or- Sauropoda: 

 Henry Fairfield Osborn. 

 In the Sauropoda the forearm is modi- 

 fied in adaptation to suppox'.t a very great 

 weight in a manner entirely analogous to 

 that in the Proboscidea, namely, the fore- 

 arm is completely rotated inward, bringing 

 the thumb, or first digit, on the internal 

 side of the foot; the ulna is also enlarged 

 proximally until it covers the entire pos- 

 terior face of the radius. This gives rise 

 to a deceptive appearance of the shafts of 

 the radius and ulna, and has led to the 

 statement that these elements do not cross. 

 Careful study of the entire, forearm, how- 

 ever, shows that the upper end of the 

 radius rises from the radial condyle which 

 is on the external side of the lower end of 

 the humerus below the deltoid crest ; on the 

 front surface of this condyle is a groove for 

 the main flexor of the forearm; immedi- 

 ately below this condyle the radius is ar- 

 ticulated, and on its front face is seen the 

 rugosity for the attachment of the flexor 

 tendon which passes through the groove in 

 the radial condyle above; these relations 

 fix the radius on the external side of the 

 limb proximally; distally the radius is 

 found on the internal side articulating with 

 the scapho-lunar and supporting the radial 

 digit, or thumb. The ulna is also strongly 

 developed on the external side of the limb 

 proximally, and extends behind the radius 

 around to the internal side, its primary 

 position ; the shaft of the ulna descends and 

 articulates with the ulnar.e on the external 

 side of the limb inferiorly. Thus when 

 seen in front view the shafts of the radius 



