Thesaurus siluricus : the flora and fauna of the Silurian period : with addenda (from recent acquistions) / by John J. Bigsby.

Date:
1868
Catalogue details

Licence: Public Domain Mark

Credit: Thesaurus siluricus : the flora and fauna of the Silurian period : with addenda (from recent acquistions) / by John J. Bigsby. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    EcHiNODERMATA.—The follo'vring little Table represents, numerically, the geographical distribu- tion of the three forms of the class Echinodermata. It is short, but contains much matter. Table K. Class Echinodermata (Geographical Summary). AMERICA. EUROPE &c. Orders. Arctic America. 1 Wisconsin. 1 N. Iowa. j Missouri. 1 Illinois. ] Indiana. 1 Ohio. 1 Kentucky. 1 Tennessee. Maryland. | Pennsylvania. 1 New York. Canada West. 1 Anticosti Island. j Nova Scotia. Newfoundland. Total Appearances (America). 1 Ireland. Scotland. j England. 1 Wales. 1 France. 1 Spain. 1 Sardinia. 1 Harz (Germany). 1 Podolia. 1 Eohemia. 1 Ealtic Russia. 1 Russia. Nucden. 1 Norway. 1 India. 1 Australia. Total Appearances (Europe &c.). Great Total Appearances. Number of Species. Number of Countries inhabited. Crinoidea Cystidea Asteriada I 19 12 2 1 3 2 2 17 1 12 5 4 42 2 1 1 2 4 71 ...lis 4515 19ll4 1.^ 3 4 1 1 2 245 66 32 5 4 1 1 53 16 19 8 24 7 2 1 2 1 1 3 1 12 3 18 7 2 32 18 2 23 10 1 7 1 1 2 158 94 36 403 160 68 315 136 61 30 19 18 3 5 1 1 1 33 1 7 18 12 8 4 45 3 4j88 77 32 6 1 3 343 10 1 88 39] 3 2 1 1 3 16 27 52 34 8 1 2 288 631 512 Table L, subjoined, shows the numerical proportions in which the species of this class occupy the successive stages of this epoch. Table L. Order. Primordial Stage. Lower Stage. Middle Stage. LTpper Stage. Total. Crinoidea 2 106 8 187 303 Cystidea 3 76 3 45 126 Asteridea 1 30 2 25 58 Its contents require no remarks. Crinoidea.—The order Crinoidea contains 78 genera and 315 * species. Thirty genera have each only one species; and these in only five cases occupy two countries. Fifteen genera have three species, and ten have two, the geographical range being here also short. A few genera are com- paratively rich in species. Thus Glyptocrinus has nineteen species, and is found in fourteen distinct areas; and Actinocrinus has fourteen species, and inhabits fourteen areas; Hypantho- crinus, with twenty-three species, is seen in ten districts. Together with great beauty, Crinoids are very sensitive to conditions, and therefore they have but a limited geographical range. The Table K will show how few Crinoids there are in many countries, such as Nova Scotia, Newfoundland, Iowa, Scotland, Spain, India, Tasmania, &c. Crinoidea have in North America two principal foci or places of concentration. There are likewise in Europe two similar chief seats. They are all singularly rich. These concentrations are in America some hundreds of miles apart: that on the west occupies Tennessee, Illinois, Wisconsin; and that on the east is met with around the City of Ottawa (Canada West) and North New York, the adjacent state of the North-American Federation. The chief seats in Europe of this order are England with Wales, and Russia with Sweden, and this in a very striking manner. These remarkable assemblages are probably due to appropriate sediments and other favourable conditions (deep sea &c.). A genus may be confined to a very few square miles, as in the case of the subgenus Cupellcecrinus * 315, from late acquisitions.