MORPHOLOGICAL REVISION I47 



single-headed ribs. The number of caudals is uncertain, but the tail was 

 certainly very long, longer than the presacral portion of the body. As 

 mounted in the American Museum, one specimen, No. 4550, has the tail 

 sufficiently long to include forty-five or more complete vertebra;; this is 

 perhaps too long. The pieces of the tail preserved do not fit and are arranged 

 according to size. The neural arches of the caudal vertebra are free and 

 rest almost equally on centra and intercentra. The arches are elongated; 

 the spines rise from far back and are very long. One nearly perfect spine 

 reaches back over the second succeeding vertebra, measuring 65 mm. The 

 chevrons are fused to the intercentra, the ends are broken so that the com- 

 plete length can not be given; one nearly complete chevron, from a point 

 near the end of series, measured 33.5 mm. Free ribs occur on the anterior 

 caudals. 



The interclavicle is rhomboid, with a sharp point to the rear; the 

 clavicles are represented by the anterior ends only; these overlap the inter- 

 clavicle below; neither the clavicles nor the interclavicle show a determinable 

 sculpture. There is a slender cleithrum with pointed anterior and clavate 

 posterior ends. The scapula can not be made out. 



The abdominal armature of scales (plate 25) underlies the clavicular 

 arch, covering the posterior end of the clavicle and interclavicle. This is 

 composed of rhomboidal scales overlapping from before backward, and 

 arranged in parallel series on each side. There are six to eight scales in 

 each lateral series. The rows of the two sides are inclined forward and 

 inward over the greater portion of the abdomen and form a chevron pattern 

 with the apex forward; but just posterior to the pectoral arch the pattern 

 is reversed, and the chevrons anterior to this point to the rear. There is 

 not a single V-shaped scale in the middle, but the scales of opposite sides 

 overlap alternately. 



The pelvis is represented by the ilium and a fragment of the ischium. 

 The ilium is much more reptilian in appearance than in most of the amphi- 

 bia; the crest has a considerable posterior prolongation to the rear; the 

 lower end is wide, showing the presence of a broad ischium and pubis. 



A femur attached to specimen No. 4550 is quite similar to that of Eryops 

 in general form, but lacks the prominent, thin keel on the anterior face. 



Measurements. 



Specimen No. 4550a, as mounted: mm 



From tip of nose to end of sacrals 820 



From sacrals to tip of tail 720 



Length of skull from anterior end of nose to middle of back of 



skull 150 



Back edge of skull to front of orbit 78 



Interorbital width 21 



Back edge of skull to anterior edge of parietal foramen 22 



Specimen No. 4550, as mounted: 



From anterior end of clavicle to tip of tail 1048.5 



Length of ventral armor 675 



Length of a femur 70.5 



A large skull No. 4551: 



Length from tip of nose to middle of posterior edge 238 



Middle of posterior edge to anterior edge of orbit 81 



Interorbital width 34 



Posterior edge to anterior edge of parietal foramen 38 



