60 



length towards the head, wliere additions are made in the form 

 of calcareous laminae beneath the coalescent joints which form the 

 base of the cup. The first radials five in number, closely opposed, 

 but not seen to be fused as in Rhizocrinus. The centre of each 

 of the first radials rises into a sharp keel, while the sides are 

 slightly depressed towards the sutures, which give the calyx a fluted 

 appearance, like a folded filter paper. Second i-adials long and free 

 from one another, joining the radial axillaries by a straight syzy- 

 gial Union, peculiar in form. A strong plate-like keel runs down 

 the centre of the outer surface, and the Joint is deepely excavated 

 on either side, rising again slightly towards the edges. The radial 

 axillary shows a continuation of the same keel through its lower 

 half, and midway up the joints the keel bifurcates, leaving a very 

 characteristic diamond-shaped space in the centre towards the top 

 of the Joint. Two facets are thus formed for the Insertion of two 

 first radials. The number of arms is therefore ten. The arms are 

 perfectly simple of few (12) joints each. No trace of pinnules, and 

 the arms resemble in character the pinnules of Rhizocrinus. The 

 first brachial is united to the second by a syzygial Joint, but after 

 that the syzygies are not repeated, so that there ist only one of 

 these peculiar junctions in each arm. The arm-grooves are bordered 

 by circnlar fenestrated plates as in Rhizocrinus. 



Ueber Pentacrinus asteria L., P. Wyville-Thomsoni 

 Jeffr., Rhizocrinus lofotensis Sars und Batliycrinus gracilis 

 W.-Th. vergleiche ferner Depths of the sea p. 337 — 450, wo 

 auch Fig. 73— 75 Abbildungen dieser Formen gegeben sind. 



Pourtales beschreibt eine zweite Art des Rhizocrinus, 

 B,. Raivsonii von Barbados, die sich durch beträchtlichere 

 Grösse, constante Fünfzahl der Arme, einfachere Bildung 

 des Wurzelendes und Anderes von Rh. lofotensis unter- 

 scheidet. Dass der untere Theil des Calyx, wie Sars will, 

 von den vergrösserten obern Stammgliedern gebildet werde, 

 wird in Abrede gestellt, der Calyx vielmehr in ganzer Aus- 

 dehnung, wie bei den jungen Comatuliden, aus einer Ver- 

 wachsung der Basalia und ersten Radialia abgeleitet. Die 

 nächsten Verwandten des Rhizocrinus sucht Verf. auch 

 nicht unter den Apiocriniden, sondern in dem fossilen Gen, 

 Belemnocrinus White. Zoological results of the Hassler 

 Expedition I. p. 26—31 PI. V. (Illustr. Cat. Mus. compar. 

 zool. VIII. 1876). 



Ebendas. liefert Pourtales auch eine kurze Be- 

 schreibung und Abbildung von Holopus Rangii. Der mit 



