NO. IGGG. OUTEOLOGY OF CA.UPTOSAURUS—GILMOKE. 279 



species, as stated on pa<i-e 277. Takintj into consideration these facts 

 in connection with many inconsistencies discovered in the figures, I 

 do not believe that the skull, as illustrated, should be considered 

 typical of the sjiecies. The teeth, as shown in fig. 9, are of the holo- 

 type, but I am unable to find that they show any distinctive charac- 

 ters. While the skull may show specific differences when the crania 

 of the other forms are known, such comparisons can not be made at 

 present, owing to the lack of material. 



The parts of the type-specimen, as enumerated above, represent a 

 considerable portion of the entire skeleton, and it is unfortunate that 

 they have not yet been made ready for study. At present only the 

 disarticulated elements of the skull and jaws, limb, foot, and pelvic 

 bones (see Plate 10) have been freed from the matrix, the other 

 parts being still largely enveloped in the hard, concretionary mass in 

 which they were originally entombed. 



Even though Marsh failed to define this form, I believe it to repre- 

 sent a valid si^ecies intermediate in structure between O. dispar and 

 C. hrowni. From C. dispar (compare Plates 15 and 16), its nearest 

 ally, it may be distinguished by the lighter structure of the pelvic 

 bones, that is, the ilium is considerably narrower in proportion to its 

 length. The oblique border of the supero-posterior end is somewhat 

 shorter. The ischium is much more slender, and the hammer-like 

 expansion of the free end less robust, its greatest diameter measuring 

 73 mm. Throughout the skeleton of G. medius aj)pears to be lighter 

 and more delicately constructed. The femur pertaining to the type- 

 specimen is proportionately very short, but I am inclined to the opin- 

 ion that this is either due to severe crushing, or the preparator, in 

 joining the two ends, has omitted a section of the shaft of the bone, 

 which would account for the extreme brevity of this element. 



Except in its smaller size, the hind foot shows no essential differ- 

 ences when compared with that of C. dispar. The following are 

 the measurements of the left pes of No. 1880 : 



mm. 



Greatest length of metatarsal I 74 



Greatest length of metatarsal II 148 



Greatest length of metatarsal III 181 



Greatest length of metatarsal IV 151 



It is anticipated that upon the complete prejiaration of the type 

 material, characters will be disclosed by which this species may be 

 more completely defined, but for the present it must rest on those 

 shown by the pelvis, although the dissimilarity shown by these bones 

 certainly suggests other and even more important differences in the 

 other portions of the skeleton. 



