II. Arbeiten von speciellerem Charakter etc. 1. Crinoidea. 255 



der wichtigsten Eigenthtiinlichkeiten iin Baue der palaeozoisclieu Crinoideen. Be- 

 sonders hervorzuheben 1st die Schilderung, welche die Verfasser auf Grund eigener 

 Untersucliimgen von den Hydrospiren der Blastoideen und Cystideen geben. Da 

 sie bei den Palaeocrinoideen analoge Organe entdeckt haben , die gleiclifalls aus- 

 fuhrlich beschrieben werden, so erblicken sie darin eine nahere Bezieliung der ge- 

 nannten drei Gruppen zueinander. In Bezug auf die Benennimg der basalen Tafel- 

 reihen schliefien sich die Verfasser an die von P. H. Carpenter pracisirte Unter- 

 sclieidung von Basalia uud Unterbasalia an. Auf die Einleitung folgt dann eine 

 Erorterung der fiir die Classification der Palaeocrinoidea vorzugsweise zu befolgeu- 

 den Gesichtspnnkte , sowie eine ubersichtliche Zusammenstellung und Definition 

 der in dern speciellen Theile der Abhandlung angewendeten Termini. In dem 

 speciellen Theile wird zuerst eine Diagnose der Palaeocrinoidea iiberhaupt gegeben, 

 die wir liier folgen lasseu. 



Palaeocrinoidea. A Suborder of the Crinoidea. 



Body, as compared with recent Crinoids, larger ; arms shorter ; test stronger. 

 The latter is arranged on various plans, but is always composed of solid plates of 

 which the interradials , in contrast to the Stomatocrinoidea , constitute important 

 elements. Plates of the aboral or dorsal side forming a cup, closed on the ventral 

 or oral side by a more or less solid integument, without external food grooves or 

 oral aperture. 



The food conveyed through openings at the base of the arms into the body, 

 and carried to the oral centre by means of internal or subtegminal passages. Anus 

 either in form of a plated tube or a simple opening, subcentral or lateral. 



The introduction of water for respiratory purposes seems to have been effected 

 through small openings or pores which penetrate the test. These openings, which 

 in some groups were located in the oral, in others in the aboral regions, seem to 

 have been connected with peculiar organs within the body, closely resembling the 

 so-called hydrospii'es of Cystideans and Blastoids. 



The Palaeocrinoids, with but few exceptions, were pedunculate, attached during 

 lifetime. Flourishing abundantly in the Silurian seas, they reach their climax in 

 the Subcarboniferous, as well in variety of form as in number of individuals, and 

 they disappear almost entirely during the Carboniferous, few forms, if any, sur- 

 viving as late as Mesozoic times. 



Die Familie der Ichthyocrinidae wird folgeudermafien characterisirt : 



"General form of the body including arms, globose to pyriform. Column strong, 

 perforation of medium size, generally pentangular. Underbasals three, of unequal 

 size ; always small, often rudimentary and not visible externally, being hidden by 

 the column. Basals five, moderately small, sometimes scarcely appearing beyond 

 the column (in Calpiocrinus probably absent or imperfectly developed) . Primary 

 radials, three to five by five, almost equal in form and size. Radials of each order 

 smaller by half than those of the preceding , and of uniform size. Arms bifur- 

 cating , short , strong , tapering upward , the tips infolding ; composed of single 

 joints. Pinnulae unknown. In most of the genera, the arms lie side by side touch- 

 ing laterally, so as to form with the calyx an apparently compact wall. Radial and 

 arm plates frequently have undulating sutures or additional patelloid plates. The 

 radials up to the second or even the third order form a part of the body, being- 

 connected laterally either by a sort of squamous integument , composed of very 

 minute, irregalar plates, or by distinct interradial and axillary plates , the former 

 varying in number from one to thirty or more, the anal area containing frequently 

 a few additional plates. Anus unknown , except in Taxocrinus and Onychocrimis, 

 which have a small lateral tube. Ventral disc rarely preserved ; composed of a 

 more or less soft or scaly integument , yielding to motion in the body and arms. 



