957 



vessel, and to alter their lines so as to satisfy the conditions of sta- 

 bility and slow rolling to any required extent. 



2. "Observations on 287 Thunder-storms made at Highfield 

 House, near Nottingham, during the last nine years." By Edward 

 Lowe, Esq., F.R.A.S. Communicated by John Lee, Esq., LL.D., 

 F.R.S. &c. 



The thunder-storms referred to in this communication are recorded 

 in a tabular form, arranged according to their dates. In this table 

 are given the date; the hour of the commencement of the storm; 

 the mean height of the barometer to tenths of an inch ; whether it 

 is rising, stationary, or falling ; the direction of the wind before the 

 storm, during its continuance, and after its cessation ; the maximum 

 temperature on the day of the storm and on the day after ; the mi- 

 nimum temperature on the night before and on the night after; and 

 general remarks on the storms. This table is followed by remarks 

 on particular storms recorded in it. In conclusion the author gives 

 the results of his observations with reference to the number of storms 

 in each year; the number in each month, with the hours at which 

 they mostly occur in particular months ; the number that have oc- 

 curred with a rising, stationary, or falling barometer ; the number 

 in respect to the direction of the wind and of the current in which 

 the storms moved ; the number of storms that have occurred at the 

 various heights of the maximum, and also of the minimum thermo- 

 meter; the number in which the peculiar breeze that suddenly 

 springs up on the commencement of thunder-storms has been well 

 marked ; the change in the direction of some of these storms, and 

 indications of rotatory motion ; and finally, the different atmospheric 

 phenomena which have accompanied these storms. 



3. " On a Dorsal dermal Spine of the Hylssosaurus recently 

 discovered in the Strata of Tilgate Forest." By Gideon Algernon 

 Mantell, Esq., LL.D., F.R.S. &c. 



In the first discovered specimen of the remains of the fossil rep- 

 tile named Hylseosaurus by the author, there were associated with 

 the recognizable parts of the skeleton a series of thin, long angular 

 processes, six or seven of which extended in a line nearly parallel 

 with the upper part of the vertebral column : these bones are from 

 four to seventeen inches in length. There are also several imbedded 

 in various parts of the same block of stone ; and in another specimen 

 of this reptile, consisting of a considerable portion of the distal part 

 of the vertebral column, similar angular bones are associated with 

 , the spine. The true nature of these processes, from their great size 

 and osseous character, was deemed very problematical : Dr. Mantell, 

 in his original memoir in 1832, regarded them as dorsal dermal spines 

 that had formed a serrated crest which extended along the back of 

 the Hylaeosaurus, in the same manner as the horny dermal fringe in 

 many species of Iguana, Cyclura, &c. Professor Owen, in his re- 

 ports on British fossil reptiles, expressed his dissent from this opinion, 

 and considered it more probable that the bones in question were 

 abdominal ribs. 



