Mr Gunti on the Silver Districts of Colorado. 155 



1882. Ophiothrix pentaphyllum, Lyman, Zool. Chall. Exp., pt. xiv., p. 225. 

 1882. ,, ,, Id., Proc. Roy. Soc, Edinb., vol. xi., p. 707. 



Habitat. British Seas. — All parts of the coast (Forbes) ; 

 Firth of Forth, Lamlash Bay, Arran (Leslie and Herdman) ; 

 Faroe Channel, 53 fathoms (Lyman). 



Other Localities. — North and west of France (Lyman). 



There is some little doubt about the distribution of this 

 species, as Forbes and Norman do not distinguish between it 

 and 0. fragilis. 



Lyman, in his " Challenger Eeport," gives its British dis- 

 tribution as '* south of Engjland," but there can be no doubt 

 about the specimens which he identified from the " Knight 

 Errant " dredgings. 



The above list contains thirty-seven species (three belong- 

 ing to the family Astrophytidse), whence it appears that the 

 number of Ophiuroids known to inhabit British Seas has 

 more than doubled during the past twenty years. 



It may also be remarked that the only species which have 

 been found nowhere else than in British Seas are three 

 (Ophiohyrsa hystricis, Ophiochiton tenuispimis, and Ophiomyxa 

 serpentaria), which were dredged by H.M.S. " Porcupine " at 

 isolated points in the Faroe Channel. Perhaps Ophiothrix 

 pentaphyllum should be added to these, as its " other 

 localities " belong to the same zoological province as the 

 British Seas, viz., north and west of France. 



XV. On the Silver Districts of Colorado (Leadville and San 

 Juan). By Henry Gunn, Esq., Assoc.Pt.S.M., etc. 



(Read 23d April 1884.) 



Abstract. 

 In the first portion of the paper, which dealt with the 

 Leadville deposits, the author pointed out that within a 

 limited thickness of from 700 to 1000 feet, typical represen- 

 tatives of Laurentian, Cambrian, Silurian, and Carboniferous 

 rocks were to be found, and also indicated the influence 

 which intrusive rocks had in the exposition of the mineral 

 veins, as all the deposits occurred at the contact of the 

 quartz porphyry with the limestones. Specimens illus- 



