440 H. GOVIEE SEELEY ON MACRUROSATJRTTS SEMNFS. 



47. On Macrurosaurtjs semntts (Seeley), a Long tailed Animal with 

 Proccelous Vertebra from the Cambridge Upper Greensand, 

 preserved in the Woodwardian Museum of the University of 

 Cambridge. By Harry Goyier Seeley, Esq., F.L.S., F.G.S., 

 &c, Professor of Geography in Kings College, London. (Bead 

 June 21, 1876.; 



About twelve years ago the Woodwardian Museum acquired from 

 Mr. W. Farren a series of some 25 associated and successive caudal 

 vertebrae, found at one of the deeper phosphatite washiugs on Cold- 

 ham Common, Barnwell. At the same date, the Rev. W. Stokes 

 Shaw, M.A., Caius College, obtained from a similar working at 

 Barton, a locality a few miles westward, another associated series of 

 15 smaller vertebras showing identical characters, and of such size as 

 to exactly join on to the first series and complete the tail. These 

 latter vertebras, not improbably part of the same individual, being 

 presented to the Museum, I arranged both sets in a continuous 

 series. Very few appear to be missing in any part of the sequence, 

 though the extremity of the tail is probably not preserved, and 

 there are no means of estimating how many vertebras may have 

 intervened between the last of the sacral region and the earliest 

 caudal which is preserved. The tail probably included 50 ver- 

 tebras, and may have reached a length of 15 feet, which would 

 have amounted to one half the length of the animal if the propor- 

 tions of modern crocodiles obtained. A few isolated vertebras 

 have also been collected; but no distinctive portions of the skeleton 

 have come under my notice. The affinities of the animal are at 

 present somewhat obscure ; for the only available data from which 

 a determination could be made are the following facts : — The 

 articulation of the earlier vertebras is proccelous ; this character 

 gradually changes till the articulations of the centrums are 

 nearly flat ; then they become biconcave, and towards the end of 

 the tail are irregular. There are no chevron bones; and the 

 centrum becomes elongated and rounded like a dice-box, after the 

 pattern of Ceiiosaurus and Loelajps. The neural arch in the greater 

 and earlier part of the tail was supported on pedicles rising from 

 the centrum ; it was depressed, and devoid of neural spine. 



The proccelous character in the caudal region has never before 

 been recorded, so far as I remember, in combination with an 

 absence of chevron bones in an animal of this size ; and though the 

 tail as a whole is more in harmony with the Lacertian type than 

 with any other order of true Eeptiles, yet we must look to future 

 discoveries for evidence of the systematic position of the animal to 

 which it belonged. In my ' Index to the Secondary Reptiles,' &c. *, 

 I classed the animal doubtfully with the Dinosauria. If it is allowed 



* Pp. xvii, 45. 



