206 J. W. Judd — On Volcanos. 



Polypary small, stout, composed of [flattened or] cylindrical dicho- 

 tomous branches ; covered by rather close obliquely annular rows 

 of exsert cellules, between which is a longitudinal rib. The cellules 

 are about twelve in a series, and are separated by spaces nearly 

 equal in breadth to the cellules. 



The rarity of Polyzoa in the English Lias increases the interest to 

 be attached to the present species, which it claims as being the pre- 

 cursor of its kind. It was noticed by the Messieurs Deslongchamps, 

 who obtained a single example, but in too bad state of preservation 

 for figuring or describing, from the Leptcena-bed at May ; whence 

 I have a very good specimen which has served for the foregoing de- 

 scription. Mr. Beesley collected several specimens from the Spinatus- 

 beds at King's Sutton ; some of them are flattened, almost foliaceous; 

 but they are not entitled to specific distinction. 



IV. — Contributions to the Study of Volcanos. 



By J. W. Judd, F.G.S. 



The Lipari Islands — Stromboli. 



{Continued from page 152.) 



IN the months of May, June, and October, 1855, and again in July, 

 1856, Stromboli was visited by M. C. Ste.-Claire Deville. He fully 

 confirms the great variations in the intensity of the explosions of the 

 volcano. On the night of the 14th of October, M. Deville, profiting 

 by a favourable condition of the wind, was able to examine the bot- 

 tom of the crater. He found three open vents within it ; one of 

 these did not project any solid matter, but the vapours above it 

 reflected a glowing light of varying intensity ; the other two dis- 

 charged stones with explosive outbursts. The largest of these mouths 

 was in the midst of a little cone of scoriae, near the centre of the crater, 

 and it gave rise to an irregular succession of detonations, interrupted 

 at intervals of about 15 minutes by explosions, producing magnificent 

 " sheaves " of incandescent stones : the other opening was at the 

 north-west angle of the crater, and gave rise to less violent explo- 

 sions at intervals of about four minutes. On the upper part of the 

 Sciarra, Deville saw, whenever the vapour drifted aside, an appear- 

 ance, concerning which he was in doubt, whether it should be 

 referred to a stream of lava, or an open fissure filled with . incandes- 

 cent material. 



On the 2nd of July, 1856, M. Deville, accompanied by M. Borne- 

 mann, again ascended to the crater of Stromboli, and they record a 

 most striking change in the condition of the crater. One very vio- 

 lent outburst took place, apparently from the mouth at the north- 

 western side of the crater, but during the two days following only a 

 series of very insignificant explosions occurred, sometimes almost 

 uninterruptedly. They gave rise to only a feeble glow of light, and 

 took place sometimes at the rate of three or four within the space of 

 a minute. 



M. Deville on several occasions carefully timed the intervals 

 between the consecutive explosions in the crater as seen from the 



