120 F. A. Bather — On Apiocrinus from the MuschelkaJk. 



pinnules on the other side, so that in this portion of the arm there 

 were no syzygies. If we assume, as seems legitimate, that this arm- 

 fi'agment represents the immediate continuation of the left-hand 

 hranch of the middle arm, then the pinnules of this arm will have 

 followed in regular alternation on all IIBr down to IlBrjg, except 

 the first and third. A portion of this arm-fragment is enlarged in. 

 Fig. 4. It shows cleaily the origin of the pinnules, and the spine- 

 like process, presumably the end of a narrow ridge separating the 

 pinnule-facet from an emhayed curve just ventrad of the distal 

 margin of the brachial. Such an appearance is not exliibited by 

 recent specimens of Calamocrinus, Peidacrhins, or Metacrinus, but is 

 fairly common in ten-armed species of Antedon, especially A. loiigi- 

 pinna, A. Mrsuta, A. Imvis, of the Tenella-gronp ; also in A. echinata, 

 of the Basicurva-groMTp. It occurs, as here, neither in the immediately 

 proximal, nor in the more distal, regions of the arm, but is most 

 obvious in the second quarter of the distichal series, or thereabouts. 



A more distal portion of an arm, lying separate on the slab, and 

 }irobably from about the tliird quarter of the arm, is represented in 

 Fig. 3. Here the ridge bounding the pinnule-facet is no longer 

 perceptible, while the embayed curve can hardly be distinguished 

 from the general curve of the distal articular surface. Two of the 

 brachials here shown are united by a syzygy (s), and form a syzygial 

 pair with a total length very slightly more than that of an ordiluiry 

 brachial from the same region. 



A small fragment, most probably belonging to the distal region of 

 an arm of this specimen, is depicted in Fig. 5. In this the brachials, 

 as usual in distal arm-tracts, have almost the aspect of axillaries, 

 though each pinnule, rapidly becoming more thin than the main 

 arm-branch, is easily distinguished from it. 



Of the Stem (Figs. 1 and 2), 46 columnals are preserved. As 

 seen in the normal position of the specimen, they are of rounded 

 appearance, with neither angles nor depressions, nor any trace of 

 cirri or cirrus-facets. The proximal 10 columnals gradually iiicrease 

 in width towards the cup, forming a cone, the sides of which are 

 continuous with those of the cup, the angle being, as Dr. Crema says, 

 about 20°. Immediately below the cone the columnals appear 

 compressed, so that the stem seems constricted to '25 mm. ; but they 

 immediately resume the normal width of about "5 mm., which con- 

 tinues to the distal end of the preserved fragment. 



The proximal columnal is thus described by Dr. Crema: "La 

 placca centro-dorsale, relativamente sottile, pressenta ben sviluppate 

 le cinque creste salienti." By "placca centro-dorsale" Dr. Crema 

 means, as so many palfeontologists erroneously mean, the columnal 

 which De Loriol has named " article basal," This phrase denotes 

 nothing more than a proximal columnal, permanent in size and 

 ])Osition, often larger than the succeeding columnals, and usually 

 marked on its proximal surface by five depressions for the five 

 basals, between whioh are five distinct ridges. In ascribing such 

 a columnal to the present specimen. Dr. Crema must have jumped 

 too rashly from a part to the whole. It was, and even now 



