Echinoidea note details

Original description
It is not quite clear which of the two works of Forbes 1852 appeared earlier and thus I was unable to establish which one of the two the "real" original description is. Plate I of Decase IV of "Figures and Descriptions Illustrative of British Organic Remains" is dated Oct. 1852 in that work, while I did not find any month for Forbes "Monograph of the Echinodermata of the British tertiaries" which was published in the same year and also includes a description of T. excavatus. Both works cross-reference each other, wherefore it is not clear which was published earlier. According to ICZN regulations the publication date for the "Monograph" - in the absence of information regarding the publication month - would need to be considered to be published on 31.12.1852, whick would make the "Figures and Descriptions..." the work that makes T. excavatus available. The genus Temnechinus, however, is only described in detail in the "Monograph", so that the original description for the genus is clear.
Forbes, E. (1852). Monograph of the Echinodermata of the British Tertiaries. <em>Palaeontographical Society London.</em> 6: 1-36. available online at 

Forbes, E. (1852). Figures and Descriptions Illustrative of British Organic Remains. Decade IV, Plate I. <em>Memoirs of the Geological Survey of the United Kingdom.</em> available online at 
2020-01-29 19:35:18Z