66 CALAMOCRINUS DIOMED^. 



the plates of the apical sj^stem of the Antedon larva with those of the 

 same system in the other orders of Echinoderms excepting the Holo- 

 thurians. Allman,* who was the first to make a detailed comparison of 

 the pre-brachial stage of Comatula with some of the extinct Crinoids, 

 recognized in the calyx and top stem joint of the young Comatula the 

 centrodorsal plate of the adult Comatula, the basals as they are found 

 in the moncyclic Crinoids, the radials, and the interradials (orals). 



The homologies of the orals of the embryo Antedon with those of the 

 genera, both recent and fossil, in which they occur, are more easily recog- 

 nized, and may for the present be left out of the discussion, referring 

 only to such pala?ozoic genera as Coccocrinus, Haplocrinus, Pisocrinus, or 

 to the x'ecent Holopus, Hyocrinus, and Rhizocrinus.t 



In my first attempt to homologize the plates of the embryo Starfish 

 with those of the Echini and Crinoids, in 18644 I compared the dorso- 

 central plate with the basal plate of Crinoids, the five plates in the angles 

 of the arms Avith the interradial plates (not the interradial plates as now 

 understood by writers on Crinoids), and the arm plates with the radial 

 plates of a Crinoid. The dorsocentral plate I considered therefore as the 

 homologue of the solidified basalia. In this view I was followed by Loven, 

 who in 1871 § regarded the single central disk in the young Echinoids as 

 homologous with that of Marsupites, the five genital pieces to be regarded 

 as basalia (infrabasals), and the five ocular as radialia (basals). This Loven 

 expanded more fully in 1874 in his " Etudes sur les Echino'idees." Loven, 

 struck by the peculiar striation existing in the plates of the apical system 

 of young Echinida? and of the Saleniae, and by the existence in those stages 

 of a large central plate, was induced to make a more detailed comparison of 

 the apical plates of the Sea-urchins with the Crinoids than had already 

 been made between Starfishes and Crinoids,|| and chose for his term of 

 comparison Marsupites.^ Loven does not seem to have seen at that time 

 my original paper on the Embryology of the Starfish, nor that on the 



* Trans. Roy. Soc. of Edinb., Vol. XXIII., 1803, p. 2il. 



t Carpenter mentions Rhizocriniis Ilawsoni as having been dredged off Panama by Captain Cole 

 of the telegraph steamer "Investigator." Thinking there must be a confusion of labels, — for the 

 " Investigator " was stationed only in the Caribbean, — I applied to Professor F. J. Bell, who kindly 

 informed me that the locality should read " Ofi Colon" (State of Panama). 



J Embryology of the Starfish, p. .50. 



§ Ofversigt af K. Vetenskaps-Akad. Foibandlingar, 1871, No. 8. 



II Embryology of the Starfish, p. 62. 



IT P. H. Carpenter has plainly shown this compaiisou of Loven to be untenable, Quart. Jouru. 

 Mici-. Sci., XVIII., Xew Ser., p. :5.57. 



