184 Echinodermata. 



Structure of the Basal Plates in Cadaster and Pentremites. in: Proc. Davenport Acad. 



N. Sc. Vol. 4 p 7687 1 Fig. on T 2 ; auch in : Geol. Rep. State Illinois Vol. 7 



p 346357 2 Figg. [188, 194, 204] 

 Wachsmuth, C., 2. Description of a new Crinoid from the Hamilton Group of Michigan. 



ibid, p 9597 3 Figg. on T 1. [194, 204] 

 Wachsmuth, Ch., & F. Springer, Revision of the Palaeocrinoidea. Part 3. Discussion of the 



Classification and Relations of the Brachiate Crinoids, and Conclusion of the generic 



Descriptions. First Section, in: Proc. Acad. N. Sc. Philadelphia p 225 364 T 4 9. 



[188, 202, 204] 



Wagner, N., Tit el s. oben p 162. [195] 

 Walter, Alfr., Ceylons Echinodermen. in: Jena. Zeit. Naturw. 18. Bd. p 365 384. [195, 



197, 199, 201] 

 Yung, E., s. Vogt. 



A. Anatomy, Physiology, Embryology. 



I. General Works (relating to all Classes). 



Ludwig gives a condensed account of the anatomy of Echinoderms in general, 

 and further notices the chief morphological characters of each class. 



Hamann compares the nervous system of Echinoderms and Coelenterates 

 and finds that it presents the same relations in the Asterids as in Medusae and 

 Actinians, i. e. forming a part of the outermost covering of the body. It is ex- 

 tremely primitive in structure, sensory cells, muscle-cells, and ganglion-cells being 

 alike epithelial in character. He also notes how the discovery of a schizocoel, coexi- 

 sting with an enterocoel in Echinoderms, affects Hertwig's coelom theory. Marshall 

 f 1 , 2 ) regards the Crinoids as having the most highly differentiated nervous system, 

 that of Asterids being an extremely primitive one. [See Bericht for 1883 I p 172.] 



Carpenter ( l ) draws attention to the great morphological differences between 

 the stalked Echinoderms and the remaining members of the group, and revives 

 Leuckart's name Pelmatozoa for a branch including three classes, Crinoidea, 

 Cystidea, and Blastoidea. The Pelmatozoa are especially distinguished by the 

 presence of a dorsal neuro-vascular centre and its frequent extension downwards 

 into the axis of a stem. This organ is altogether unrepresented in other Echino- 

 derms which also make use of the water vascular system for locomotive purposes, 

 while its functions are much more limited in the Pelmatozoa, and it does not com- 

 municate directly with the exterior. For a comparison of the actinal and abactinal 

 systems of the Pelmatozoa with those of other Echinoderms see infra p 1ST Car- 

 penter (*). 



Perrier ( 5 , 6 ) confirms W. B. Carpenter's statements that the genital rachis of 

 the Crinoid arm originates in the dorsal organ , and is led to consider the arms 

 as reproductive individuals arranged around a central one. An Echinoderm is 

 thus comparable to a Medusa consisting of a central Gastrozooid and an umbrella 

 formed of united Dactylozooids. 



Perrier ( 4 , 6 ) starting from his conception of the vascular apparatus of the 

 Crinoids [see p 187] divides the Metazoa into two groups, the Zoophytes, inclu- 

 ding Sponges, Polypes, and Echinoderms, and the Artiozoa. The Zoophytes are 

 animaux originairement fixes, a 1'apparence vege"tale ou a sy me trie rayonnee. 

 chez qui circule de l'eau. 



Carpenter ( 4 ) denies the presence of excurrent openings in the Crinoids [see 

 p 188] and points out that the fundamental unity of the double vascular system 



