116 CATALOGUE OF THE BLASTOIDEA. 



Echinoderms." This position was assigned to them independently by Professors 

 Leuckart, Huxley, and Ray Lankester ; and the course taken by these distinguished 

 naturalists has received the approval of the late Sir Wyville Thomson and Dr. 

 Carpenter, of Mr. Percy Sladen, and lastly of Professor Hubert Ludwig. 



Messrs. Wachsmuth and Springer 1 , however, while employing Leuckart's name 

 Pelmatozoa, use it only as equivalent to Crinoidea as defined by Eoemer, Zittel, and 

 de Loriol, i. e. merely as a class name, of equal rank with Urchins, Starfishes, or 

 Holothurians. 



They admit that the Stalked Echinoderms are more distinct from either of the 

 three groups of Echinozoa than these are among themselves ; but they doubt the 

 necessity of expressing this in a classification for fear of its becoming encumbered by 

 too many subdivisions. There appear to us, however, to be just as good reasons for 

 dividing the Echinoderms into branches Echinozoa and Pelmatozoa, as for making 

 Branchiata and Tracheata primary divisions of the Arthropods, or for grouping the 

 five classes of Vertebrates into Ichthyopsida, Sauropsida, and Mammalia. Leuckart 2 

 pointed out in 1848 that the result of the researches of Miller and Muller was to 

 show " dass die Crinoiden keineswegs mit den Asteriden vereinigt werden durfen, 

 dass sie vielmehr eine besondere, u. a. durch fundamentale Unterschiede in der 

 Skeletbildung ausgezeichnete Gruppe bilden." 



To any one acquainted with the progress of Echinoderm morphology during the last 

 forty years this sentence will have an even deeper meaning than it had when Leuckart's 

 most valuable essay was published in 1848. The remarkable neuro-vascular system 

 which is situated in the anti-ambulacral region of a Crinoid and extends downwards 

 into the stem, probably to control its movements and those of the cirri which it 

 often bears, was utterly and entirely misunderstood by the majority of naturalists 

 until quite lately ; and we think that the American palaeontologists can be scarcely 

 aware of its morphological importance. 



The only differences between the Pelmatozoa and the other Echinoderms to which 

 they refer are purely of a physiological nature, viz. the absence of locomotor organs 

 in connection with the ambulacral system, and the fact that a Crinoid lies on its 

 aboral surface instead of creeping about with its mouth downwards in search of 

 food. They conclude by saying \ " All this, however, we think is sufficiently 

 expressed by giving the Pelmatozoa the rank of a class, and placing them at the end 

 of the list." But since " this " is not " all " we cannot accept their view of the 

 systematic position of the Pelmatozoa, and, like Leuckart, Huxley, Ilaeckel, Ray 

 Lankester, and Ludwig, we prefer to rank the group as a distinct " Branch " of the 

 " Phylum " Echinodermata. 



The authorities just mentioned, and also Eoemer, Eorbcs, and Claus, have regarded 

 the Brachiate Crinoids, the Cystids, and the Blastoids as groups equivalent to one 



1 ' Revision of tho Palicocrinoirloa,' Part III. 1885, p. 75. - Op. cit. p. 39. 



3 ' Revision of the Puloeocrinoidea,' Part III. 1885, p. 75. 



