PEKIODICITY IN ORf;ANIC JJKE. 



51 



There is no very remarkable feature to record ; but the general 

 condition of the bones gives evidence of a non-adult animal, 

 especially the epiphyses of the dorsal and lumbar vertebrae, which 

 are distinct, though loosely adherent to the body of each vertebra. 

 In the cervical vertebrae they are nearly free, and in the caudal they 

 are mostly loose plates. Mr. Gerrard informs me that the vestigial 

 remains of the hind limbs were only two small pieces of cartilage. 



The s/er/iu)ii of this species differs very greatly in individuals, 

 and varies also in shape, according to the age of the animal. The 

 median notch in the prestermiin forms, in the Burnham specimen, a 

 relatively large pear-shaped sinus. 



It may be interesting to append a few of the measurements I was 

 enabled to make : — 



ft. 



Skull . 



Length, minus a few inches broken off tlie ends 



of premaxilla*, measured in a straight line 

 Breadth, at zygomatic process of squamosals 

 Length of each ramus, straight line 



,, ,, in curve 



Greatest breadth, including transverse processes 



,, height, base to apex of neural arch 

 Breadth .... 



Height 



Median opening of presternum 

 Width of sinus 



Base of sinus to xiphoid point 

 Breadth .... 

 Height, straight line . 



„ base to end of median notch 

 Greatest breadth .... 

 Width, supra-scapular border to the glenoid cavity 



P.S. — Since the above was written, I have been informed by Mr. 

 A. Newman that he has sold the skeleton, and it is now in a museum 

 at Grimsby. 



Mandihle 



Atlas 



Slt'iinnn 



Ilyoid 

 Scapula 



PERIODICITY IN ORGANIC LIFE. 



By HENRY LAYER, M.R.C.S., F.L.S., F.S.A. 

 Being the Presidential Address, deli-'cred at Chelmsford, April ijth, iSgj.} 



T HAVE used this term " Periodicity " to indicate that state or 



condition of a species, either animal or vegetable, which most 



of those who have paid much attention to natural history in any of 



its branches must have noticed, I mean that there are periods, not 



E 2 



