240 



T. Coan on the Eruption at Hawaii. 



as described in vol. xx ( p. 22 of this Journal. The shell is 

 found in the same coarse grit as the Clathropteris, immediately 

 beneath the trap (see section in the paper just referred to). 



By referring to Bronn's Lethaea Geognostica, I find that the 

 Budistas with the exception of the genera — Orbicula and Cra- 

 nia, are confined almost wholly to the Chalk Formation, and 

 the shell from Mount Tom certainly comes nearer to the 

 genus Sphgerulites, Badiolites and Hippurites, than to Crania. 



This specimen is too imperfect to allow of a specific or generic 

 description, but if there be no mistake in associating it with the 

 above genera, it seems to lend additional strength to the inference 

 derived from the discovery of the Clathropteris, that the upper 

 part of the Sandstone of the Connecticut Valley is as high at 

 least as the Liassic or Jurassic series. It might seem even to 

 carry us higher in the series, but it would be premature to draw 

 such an inference from a single imperfect specimen, even though 

 its true analogies be ascertained. The specimen now belongs to 

 Amherst College Cabinet. 



Art. XX. — On the Eruption at Hawaii; by Be v. Titus Coan.* 



Ere this you may have seen my letter of Nov. 16th to Mr. 

 Lyman, giving an account of a visit to the end of the lava stream 

 in the forests of Hilo. Since that date I have made four trips to 

 the fire, making six in all. The great fire fountain is still in 

 eruption, and the terminus of the stream is only about five miles 

 from the shore. A track for horses has been cut to the fire, so 

 that we can now ride up with ease and return in half a day. 

 The lava moves slowly along on the surface of the ground, and 

 at points where the quantity of lava is small, we dip it up with 

 an iron spoon held in the hand. During the last three weeks the 

 stream has made no progress towards Hilo, and we begin to hope 

 that the supply at the summit fountain has diminished. There 

 is, however, still much smoke at the terminal crater ; and while 

 the lower end of the stream is hardened for two miles above its 

 terminus, thus checking the flow in the forest, the fusion is by 

 hydrostatic pressure, gushing up vertically above this line, and 

 creeping, like fiery serpents, in a thousand gory looking rills, 

 over the smouldering masses of lava, long since deposited. These 

 repeated and numerous up-gushings of the fusion through cracks, 

 holes and fissures in the superincumbent masses of recently 

 solidified lava, are caused by the sudden hardening of the end of 

 the stream, thus obstructing the passage and causing the incan- 

 descent material, flowing under cover from regions above, to force 



* From a letter to J. D. Dana, dated Hilo, March 7, 1856. 



