II. Pelmatozoa. 7 



whorl of cirri developed, and also notices a monstrous ray with the 2 arms fused 

 together from the third joint above the axillary. 



Mac Mlinn ( 3 ) notes the remarkable resemblance between the reactions of purple 

 pentacrinin and those of some flowers, e. g. Iris. It is also very similar to 

 bonellein. 



Wagner gives a minute account of the morphology of the skeleton in 3 spe- 

 cies of Encrinus. E. gracilis, with its relatively large basals, is a persistent larval 

 form, and perhaps the phylogenetic starting point of the whole .E.-series. 



Walther, applying Haeckel's scheme of Medusoid structure to the Crinoids, 

 finds 3 axes in the Calyx. I. Perradial, on which the first skeletal plates, basals 

 and orals, are developed. II. Interradial, on which the Radials appear. III. 

 Adradial, between I. and II. In the archicyclic stage the calyx consists of 5 basals 

 and orals (perradial) and 5 interradial primary Embryonal-Pinnulae. These 

 are the 5 primary tentacles extended from the water- vascular ring , but it is 

 more than probable that they are young stages of the jointed pinnules which are 

 ultimately developed at the sides of the arms. In the next stage there appear, 

 adradially, 10 more Embryonal-Pinuulae ; and with the appearance of the inter- 

 radially placed Radials on Axes II, the principal morphological axes are shifted 

 36, while the principal morphological plane is raised from a lower to a higher 

 horizon. The arms are developed mterradially (II) , but then fork and become 

 adradial on Axis III. The primary interradial Embryonal-Pinnulae remain, how- 

 ever, 1 in each fork, as its primary median pinnule ; and it becomes the more or 

 less prominent process between the 2 articular facets of the radial axillary which 

 is so evident in many Crinoids. The development of the dicyclic from the mono- 

 cyclic condition , like that of the monocyclic from the archicyclic, depends on a 

 further shift of the morphological axes through 36, in the same direction as the 

 spiral twist of the gut which results from it. - - On the assumption that the Em- 

 bryonal-Pinnulae are true pinnules it is concluded that the pinnules are of 

 higher morphological value than the arms, which are merely the pinnule-bearers. 

 The following propositions are also formulated. The Pelmatozoa originated in 

 pre-Cainbrian times from a bilateral ancestor, the Silurian Ateleocystites retaining 

 the bilateral symmetry. Fixation induced a radiate symmetry, representing the 

 archicyclic stage of ontogeny, and illustrated by the Cambrian Macrocystella with 

 numerous jointed appendages round the mouth. At this stage the Crinoids and 

 Cystids began to diverge, the former having 5 terminal fixed points in the calyx- 

 structure, nomalocyclic growth, and well developed arms with the genital glands 

 in their pinnules; while the Cystids are anomalocyclic , without terminal fixed 

 points, and internal genitalia. Porocrinus represents an attempt at the Crinoidal 

 mode of development on the part of a Cystid. 



The concluding portion of the Revision of the Palaeocrinoidea by Wachs- 

 muth & Springer is mostly of a systematic character, but many morphological 

 observations are incorporated in it. The rays and arm-bases of Crotalacrinus are 

 described as having a ventral covering of comparatively heavy interradial plates 

 which is supposed to have been pliant. In accordance with the suggestion of Car- 

 penter the consolidating apparatus of Cupressocrinus is described as consisting of 

 the united muscle-plates of the radials, from the lower portions of which they are 

 apt to separate. Recurrent ambulacra, like those described by Carpenter in Hy- 

 bocystites [see Bericht for 1882 I p 180], also occur in Taxocrinus elegans and T. 

 laevis. The Encrinidae are Palaeocrinoids , being intimately related to the Pote- 

 riocrinidac. The calyx-structure of Catillocrinus and Calceocrinus is redescribed. 

 Stephanocrinus is not a Blastoid at all, but a Brachiate Crinoid, having branching 

 biserial arms arranged somewhat as in the Platycrinidae. The supposed lancet 



Zool. Jahresbericht. 1886. Eckinodermata.. d 



