MORPHOLOGICAL REVISION OF THE SUBORDER. 145 



The pubis has lost the distal end, so that its exact length can not be given, but 

 it was evidently fully as long as the ischium. The obturator foramen is large and 

 oval in outline and lies under the middle of the acetabulum very close to the posterior 

 end of the pubis. 



The posterior limb is unknown. 



Naosaurus claviger was a short, stumpy animal with a round barrel and a large 

 head. The head was proportionately quite large and the tail was almost rudimentary 

 in its abbreviation. The limbs were short and robust, and the supporting pelvic and 

 pectoral girdles were proportionately heavy. The attitude when at rest must have 

 been with the belly on the ground, but when walking the limbs were probably 

 straightened enough to swing the belly just free. In studying the proportions one is 

 constantly reminded of the body of a particularly sturdy hog with strong limbs; the 

 motion in walking must have been singularly like that of a hog, a waddling gait with 

 the head held low. Compare plate 35. This restoration by the American Museum 

 gives a good idea of the form of the animal. The anterior cervicals are restored from 

 Dimetrodoii and are, in my opinion, wrong; the anterior cervicals were probably 

 smaller with low spines. The skull is modeled from D. gigas, and is wrong if, as 

 suggested in the note below, the true skull is that of Edaphosaiirus. The tail seems to 

 me to be rather too long. 



Measurements. — -No. 4002 American Museum. 



mm. mm. 



Length, bottom line of centrum of vertebrae; Length, bottom line of centrum of vertebrae: 



ist (3d cervical) 26 19th 38 



2d 29 20th, about 41 



3d 27 2ist (broken) 



4th (broken) 29 22d 36 



5th 34 23d 36 



6th 37 24th 33 



7th 36 25th (ist sacral) 25 



8th (broken) 37 Total length of same 38 



9th 42 Length, bottom line of centrum of 26th vertebra.- 31 



lOth (broken) 42 Total length of same 42 



nth 41 Length of spine of — 



I2th 44 6th vertebra (8th from atlas, broken) about 475 



13th 44 7th vertebra 485 



14th 48 18th vertebra (7th presacral) 465 



15th 43 2rst vertebra (4th presacral) 235 



i6th 43 Length of imperfect symphysis 237 



17th 39 Antero-posterior diameter of acetabulum 75 



i8th 39 



No. 4015 American Museum. 



Length, bottom line of ist vertebra (4th cervical).. 25 Height of incomplete spine of same 178 



Height of incomplete spine of same 108 Length, bottom line of 3d vertebra (6th cervical).. 28 



Length, bottom lineof 2d vertebra (5th cervical).. 28 Height of incomplete spine of same 205 



No. 4146 American Museum. 



Greatest length of incomplete scapula 335 Probable total length across curve 350 



Greatest diameter of humeral cotylus 80 mm. 



Note. — During the past summer ( 1906) the author conducted an expedition into the Permian beds of Texas, 

 and a specimen discovered suggests a rather different interpretation of the position of Naosaurus. In a bed 

 of sandstone which had never before yielded fossils there were found several spines of N. microdus and 

 several fragments of a skull ; notably, the typical plate with crushing teeth from the upper or lower jaw of 

 Edaphosaurus. From the occurrence of the specimen in a sandstone otherwise barren and far from any 

 other remains the association seems certain, though the fragments of the skull were loose in the wash just 

 below spines which were partly in position. It will be remembered that the type specimen of Naosaurus 



