from the O.rfonl Clit/ of Peterborough. A'l\. 



Tliis genud is represented at present by only one species, 

 for which is proposed the name IricleiJus seeleyi, after the 

 late Professor II. G. Seeley, who wrote a number of papers 

 on these Oxford Clay Keptilia. The type specimen upon 

 which the species is founded consists of the greater part of 

 the skeleton of an individual in which, in spite of its small 

 size, ossification was complete, so far as completeness is 

 indicated by the union of the coracoids and scapidaj in the 

 middle line (fig. 1), the rounding of the heads of the humerus 

 (fig. 2) and femur, and the fusion of the arches witli the 

 centra of the cervical vertebrw. ]\Iost of the bones of the 

 skull are separated from one another, but it can be seen that 

 the structure must have been much as in MurcBnosaurus. 

 The teetii in the mandible are particularly well preserved, 

 many of the slender curved crowns being complete. The 

 seiies of cervical vertebrae seems to be complete; they are 

 twenty-six in all. The shoulder-girdle is complete (fig. 1) 

 and siiows the peculiar clavicular arch very well preserved. 

 The fore-paddle (fig. 2) shows the articulation distally with 

 four distinct elements. A detailed account of this skeleton 

 will be given later. 



Some dimensions (in centimetres) of the type specimen 

 (R. 3539) are :— 



Leng'th of basioccipital 34 



„ from occipital condyle to anterior end 



of parasphenoid 8 8 



„ of mandible 25-0 



„ of atlas and axi.-* 40 



,, of sixth cervical 23 



Width of „ „ 2-8 



Height of „ „ . 2-3 



,, to top of neural spine of sixth cervical . 5'7 



Length of shoulder-pirdle in middle line 53'0 



,, of interclavicle 6-4 



Width of „ 13-8 



Length of coracoid 39*6 



Least width of coracoid 13'1 



Length of humerus 20'7 



Width of distal end of humerus 11-8 



l^ength of femur 21 -O 



Width of distal end of femur 113 



PiCUOCLEiDUS, gen. nov. 



This genus is now established for the reception of Seeley*s 

 Murcei^osaurus helocb's, which differs from Marcvnosaurus in 

 some important respects. The genus may be defined as 

 follows: — 



Small Plesiosaurs in which the neck is composed of 



