MITEJiNOSAUEUS LEEDSI. 



i2i 



approaching completion. (2) The greater length of the centra of the cervical vertebree 

 compared to their width, particularly in the hinder part of the neck ; in this region 

 also in this species the centra are longer in proportion to their height, and the articular 

 ends are more oval than in M. darohrivensis. (3) The presence of a strong longitudinal 

 crest on the side of the cervical centra just above the rib-joint distinguishes this 

 species from M. diirohrivensis but not from M. plcdz/clis. (4) The interclavicle, in some 

 cases at least, is produced back in the middle line into a median process (PI. VI. 

 fig. 6 ; text-fig. 62) instead of bearing a median posterior notch, as in 3f. dtirohrimnsis 

 (PI. V. fig. 10) and M. plafyclis (PI. VI. fig. 3). (5) The limbs appear to be more 

 lightly constructed than in the other species (text-fig. 63). 



All the following specimens from the Leeds Collection were obtained from the 

 Oxford Clay in the neighbourhood of Peterborough. 



R. 2421 (Leeds Coll. 25). Imperfect .skull and skeleton. The parts present are : — Basioccipital, 

 exoccipitals, basisphenoid, parts of maxilla, premaxillse, portions of pai'ietals and frontals, 

 portions of the mandible ; forty-four cervical vertebrse, two pectorals, nineteen dorsals, 

 and twelve sacrals and caudals ; many of the vertebriB have the fused neural arches 

 preserved, and in some of the cervicals and caudals the ribs are preserved; dorsal ribs; 

 portions of coracoids and scapulaj ; fore paddles (phalangeal portion incomplete) ; 

 ilium; ischia ; hind paddle (phalangeal portion incomplete). Type specimen described, 

 and figured by Seelcy, loc. cit. supra (also figured in Plates III. & IV.). 

 The dimensions (in centimetres) of this specimen are : — 



Skull (PI. III. figs. ], 2): 



Basioccipital ; transverse diameter of occipital condyle . . 2-2 



vertical diameter of occipital condj'le . . . 2'2 



greatest length in middle line 3'9 



„ width at lateral processes .... 5'1 



Width across snout at inaxillo-pretnaxillar}'' suture .... 6'3 

 Mandible (PI. III. fig. 3) : 



Length from anterior end of symphysis to angle .... 34-0 



„ of symphysis 5-2 



„ of post-articular region 4*1 



Vertebra: CerTicoal3\ Atlas ami Tliird Fifth Klercntli Fifteenth ^""^"^•^' 



(PI. IV. figs. 1-4) J axis. cervical, cervical, cervical. 



Length of centrum in mid- 



3'6 4-2 



3-7 4-3 



3-1 3-5 



7-8 



ventral line 



Posterior width of centrum . 



„ height of centrum . 



Height to top of neural spine 



5-3 

 3-3 

 3-1 



2'7 

 3-5 



3-0 



Fifteenth 

 cervical. 



4-7 

 4-9 

 3-8 



fourth 

 cervical. 



5-5 



Thirty- Fortieth 



second cervical 



cervical, (crushed). 



5-6 



Vertebi-a; : T Second 



Pectorals, Dorsals, etc. J pectoral. 



Length of centrum in mid- 

 ventral line 4'9 



Posterior width of centrum . 6-6 



„ height of centrum . 5-2 



Dorsal 

 (forty- 

 ninth). 



5-6 



Dorsal 



(fifty- 



eighth). 



5-2 



6'0(app.) 6-0 

 5-7 4-7 



Dorsal 

 (sixty- 

 third). 



4-8 

 6-0 

 4-6 



O'd 



6-8 

 .5-4 5-5 

 lG-9 19-8 (app.) 



Saci-al Caudal 



5-4 (app.) 5-9 

 4-7 

 14-4 



(sixty- 

 eighth). 



3-9 



e-0 



4-2 



(seventy- 

 fifth). 



3'8 

 5-4 

 4-0 

 K 



