Intelligence and Miscellaneous Articles. 77 



Dall ; 5. T. ? galtensis, Bill., = minor, Ball ; 6. T. ohioensis, Meek ; 

 7. I 7 . Da7/i, Dav. & King ; 8. T. ivisbyensis, Dav. & King. 



Genus 2. Monomerella, Billings (1871). Sp. 1. M. prisca, Bill. : 

 2. il/. Walmstedti, Dav. & King ; 3. ikf. Lindstrbmi, Dav. & King ; 



4. M. orbicularis, Bill. 



Genus 3. Dinobolus, Hall (1871). Sp. 1. D. Conradi, Hall; 

 2. i). Davidsoni, Salt. ; 3. Z). canadensis, Bill. ; 4. Z). transversus, Salt. ; 



5. 2). Woodwardi, Salt. ; 6. D. magnificus, Bill. ; 7. Z). Schmidti, sp. n. 

 The authors further discuss the characters of Professor Hall's 



Lingidops Whitfieldi, which they regard as in some respects inter- 

 mediate between the Lingulidse and Trimerellidae, and describe under 

 the name of Chelodes Bergmani a fossil sent to them by Dr. Lind- 

 strom under the impression that it was a Trimerellid. They indicate 

 its points of resemblance to Trimerella, but think that it really 

 belongs to the section of the Coclenterata represented by Calceola 

 and Goniophyllum. The fossil is from the isle of Gothland, and 

 was obtained from a formation equivalent to the Aymestry limestone. 



X. Intelligence and Miscellaneous Articles. 



PERMANENT ICE IN A MINE IN THE ROCKY MOUNTAINS. 

 BY R. WEISER, OF GEORGETOWN, COLORADO. 



GEOLOGISTS have been not a little perplexed with the frozen 

 rocks found in some of our silver-mines in Clear Creek Co., 

 Colorado. I will first give a statement of the facts in the case, 

 and then a theory for their explanation. 



There is a silver-mine high up on McClellan Mountain, called 

 the " Stevens Mine." The altitude of this mine is 12,500 feet. 

 At the depth of from 60 to 200 feet the crevice matter, consisting 

 of silica, calcite, and ore, together with the surrounding wall-rocks, 

 is found to be in a solid frozen mass. McClellan Mountain is one 

 of the highest eastern spurs of the Snowy Range ; it has the form 

 of a horseshoe, with a bold escarpment of felspathic rock near 

 2000 feet high, which in some places is nearly perpendicular. The 

 Stevens Mine is situated in the south-western bed of the great 

 horseshoe; it opens from the north-western. A tunnel is driven 

 into the mountain on the lode, where the rock is almost perpen- 

 dicular. Nothing unusual occurred until a distance of some 80 or 

 90 feet was made ; and then the frozen territory was reached, and 

 it has continued for over 200 feet. There are no indications of a 

 thaw summer or winter ; the whole frozen territory is surrounded 

 by hard massive rock, and the lode itself is as hard and solid as the 

 rock. The miners being unable to excavate the frozen material by 

 pick or drill to get out the ore (for it is a rich lode, running argen- 

 tiferous galena from 5 to 1200 ounces to the ton), found the only 

 way was to kindle a large wood fire at night against the back end of 

 the tunnel and thus thaw the frozen material, and in the morning 

 take out the disintegrated ore. This has been the mode of mining 

 for more than two years. The tunnel is over 200 feet deep, 

 and there is no diminution of the frost ; it seems to be rather 

 increasing. There is, so far as we can see, no opening or channel 

 through which the frost could possibly have reached such a depth 



