INTRODUCTION. 9 



the Crinoids ; a second Class, the Actinozoa, with two orders, the Urchins 

 and Asterids (including Ophiurids) ; and a third Class, the Scytoderinata, 

 with two orders, the Holothurians and the Sipunculids. After the publi- 

 cation of his Morphologic, Leuckart himself does not seem to have laid 

 great stress upon some of his suggestions for new classification. In his 

 Report for 1848 to 1853 he only refers incidentally to the name Pelmato- 

 zoa, and divides the Echinoderms into, 1. Holothurida, 2. Echinida, 3. Aste- 

 rida, 4. Ophiurida, 5. Crinoidea. In his Reports for 1854-55 and for 1856 

 the same nomenclature is followed. In his Report for 1857 he speaks of, 



1. Scytodermata, 2. Actinozoa (Echinida, Asterida, Ophiurida), 3. Crinoidea. 

 For 1858 his Report corresponds with that of 1857, and it is only in his 

 Report for 1859 that we find the name Pelmatozoa reappear, ten years 

 later than its first introduction. In his Report for 1859 we find the 

 Echinoderms divided into, 1. Scytodermata, 2. Actinozoa, 3. Pelmatozoa. 

 In 1861) he again drops the name Pelmatozoa, and we find, 1. Scytodermata, 



2. Actinozoa, 3. Crinoidea. The same nomenclature occurs again in his 

 Reports for ISGl and 1862, and for 1863. In that for 1864 and 1865 

 we find the nomenclature as stated in the Report for 1859, Pelmatozoa 

 being again introduced. Then for a series of years, 1866 and 1867, 1868 

 and 1869, 1870 and 1871, and 1872 to 1875, he speaks in those Reports 

 of Pelmatozoa ; while in the last Reports by Leuckart, in Wiegman's 

 Archiv, he again, 1876 to 1879, introduces, 1. Scytodermata, 2. Actinozoa, 



3. Crinoidea. 



The name Pelmatozoa was not adopted by any writer on Crinoids ex- 

 cept, as Carpenter states, by Sir Wyville Thomson * in the Syllabus of his 

 Lectures ; and, as is seen from what has preceded, Leuckart himself used 

 indiscriminately Crinoidea or Pelmatozoa. It is therefore not siu'prising 

 that Roemer should not have adopted Leuckart's name, and should have 

 continued to retain the name of Crinoids for the group as a whole, al- 

 thouo-h reco2;nizino; the si;reat distinction existing between the Brachiate 

 Crinoids, the Blastoids, and the Cystids. 



The confusion which has arisen in the nomenclature of the primary di- 

 visions of Echinoderms illustrates the difficulty of attempting to retain old 

 and familiar names as descriptive of groups when limited by more recent or 

 more extended knowledge, or by applying to these older names ideas of 

 nomenclature entirely unknown at the time they were first adopted. To 



* Syllabus of Lectures on Zoology, Edinburgh, 1878. 



