794 



SCIENCE 



[N. S. Vol. XXIX. No. 750 



coracoids and sternal plates. The upturned 

 ribs were also without compression, affording 

 a normal section of the chest. The hind 

 limbs were drawn up and doubled on them- 

 selves. The animal thus occupied a space of 

 10 X 12 feet. The precise position of the ele- 

 ments of the pectoral arch and chest is not the 

 least important feature of the discovery. 



The most important feature is the complete 

 encasement of aU parts of the body which are 

 preserved in a natural cast of the impression 

 which the epidermis made upon the matrix, 

 affording for the first time complete data as to 

 the skin structure of the Iguanodonts. Some 

 of the outlying parts of the epidermis, especially 

 along the neck frill, at the extremities of the 

 manus, and along certain border regions, were 

 cut into apparently before it was realized that 

 the epidermal cast was preserved ; but at many 

 important points these impressions are per- 

 fectly shown, especially on the throat and an- 

 terior part of the neck, on the arms, and fore 

 limbs, on the entire right side of the body, and 

 over a large part of the ventral surfaces, in- 

 cluding the axillary regions and especially 

 over the abdomen. Most remarkable is the in- 

 flection of the skin like a curtain along the 

 lower border of the ribs, over the entire ab- 

 dominal region without a single break, with 

 brilliant impressions of the scale pattern. 

 Equally significant are the sharp skin folds 

 over the sides of the body and in the axillsa, 

 at the throat, and along the flexor surfaces of 

 the arms. This abdominal infolding, the close 

 appression of the skin to the surface of the 

 bones, the sharp transverse folds, all indi- 

 cate that after death the body had been ex- 

 posed for a long time to the sun, that the 

 muscles and viscera had become completely 

 dehydrated; in other words, the body had be- 

 come thoroughly dried and mummified, while 

 the epidermis became hardened and leathery 

 under the action of the sun. In this condi- 

 tion the dinosaur mummy had been caught in 

 a freshet and rapidly buried in fine river sand 

 which took a perfect cast of the epidermal 

 markings before the tissues disintegrated 

 under the solvent action of the water. 



The first and most surprising impression is 

 that the epidermis is extremely thin, and that 



the markings are excessively fine and delicate 

 for an animal of such large dimensions. There 

 is no evidence in any part of the epidermis 

 either of coarse tubercles or of overlapping 

 scales. In all parts of the body observed it is 

 entirely composed of scales of two kinds : (1) 

 larger pavement or non-imbricating scales, 

 (2) smaller tubercular scales. 



The former are perfectly smooth and non- 

 imbricating, like the pavement head scales on 

 the Lacertidse. As grouped in clusters or 

 rosettes they are rounded or irregularly polyg- 

 onal. Over the throat, neck, sides and ven- 

 tral surface these clusters are regularly dis- 

 posed in definite patterns, separated by areas of 

 finer tubercular scales, but in the tail, as indi- 

 cated in another specimen, it is probable that 

 the cluster arrangement disappears and that 

 the entire tail is covered with the tessellated 

 or pavement pattern, including scales of larger 

 size, although this may be a matter of specific 

 difference. In many existing lizards we ob- 

 serve a strengthening of the scales in the 

 caudal region, and the vigorous use of the 

 tail ' among Iguanodonts as a balancing and 

 perhaps partly as a swimming organ, would 

 lead us to expect stronger scales in the tail 

 region. 



As observed on the sides of the body just 

 above the scapula, the pavement scale clusters 

 are 3.5 to 4.5 cm. in diameter. In the center 

 of the cluster the scales are about .5 cm. in 

 diameter, and toward the borders they dimin- 

 ish to .35 cm., while the outlying tubercular 

 scales number six or seven per centimeter. 

 These clusters run in definitely arranged pat- 

 terns, which will be fully described in a later 

 communication, from the sides around the 

 under surface of the body. 



On the side of the throat in the region just 

 back of the quadrates are much larger clusters 

 of these flattened scales, but beneath the 

 throat there is again observed the alternation 

 of the clusters with intermediate tubercular 

 areas. A large cluster is beautifully pre- 

 served on the upper arm, half way between the 

 elbow and shoulder, but the lower arm seems 

 to be chiefly covered with the small tubercular 

 scales, although some pavement scales may 

 also be observed. On the forearm the skin 



