F. A. Bather — On Apiocrinus/roin the Manchelkalk. 119 



A further point of importance in this connection is the separation 

 of the arms from one another by a space beginning, as above 

 intimated, on the shoulders of the radials ; while the absence of 

 preserved inter-brachial plates in this space suggests that it was 

 tilled, if at all, only by a flexible extension of the tegraen, in which 

 such plates as may have existed can only have been minute and 

 loosely united. In short, there was nothing to impede the perfectly 

 free movement of the arms which we have already inferred. 



The Primibrachs (IBr) are two. Their width is slightly less 

 than that of the radial, but they expand a little upwards. IBrj 

 has a height of little less than half its own width. Conspicuous on 

 IBrj of the middle arm is a clear, fine groove slanting downwanls 

 from the left upper angle to a little below the middle of the right 

 side. A somewhat similar marking is less evident on IBrj of the 

 arm on the right. This line may indicate the compound origin of 

 IBrj, and may even be caused by a syzygial suture, such as occurs 

 at the same level in Calamocriiius Diomedecs; but it is hardly 

 definite enough to permit one to speak of three primibrachs. Each 

 IBri further shows a faint groove close to, and parallel with, its 

 distal margin, IBrj, the axillare (lAx), is about '75 mm. high and 

 l"4mm. wide. In the middle and right-hand arms it lies at an 

 angle to IBr^ forcibly suggesting that here also the union was 

 articular. 



Of the Secundibrachs (TIBr), three are preserved in each distichal 

 series of the middle and right-hand arms. IlBrj and IlBr.^ are 

 Bubquadrate, about as high as wide, expanding upwards slightly. 

 IlBr^ bears no pinnule. In the right-hand branch of the midille 

 arm and the lett-hand branch of the right-hand arm, llBv^ bears 

 a pinnule at its outer upper comer. This was probably also the 

 case with lIBr^ in the other branches. IIBrj is narrower than 

 the preceding, and seems to have borne no pinnule, but was most 

 probably joined to IIBr^ by a syzygy — a fact that would explain 

 the snapping off of all the branches at this level. 



On the suture between llBr^ and llBr^ in the left-hand branch of 

 the right-hand arm, is seen a small upward bend, which represents 

 the end of the fulcral ridge, and indicates that, as one would expect, 

 this union was a perfect articulation. 



The first Pinnules (Fig. 2), like those in more distal regions of 

 the arm (Figs. 3 and 4), are thin, and composed of ossicles with 

 a length three or four times their own -width, and with slightly 

 hollowed sides. Similar pinnules are possessed by the adult Antedon 

 longipinna, but seem to be common to all young Antedons, and 

 perhaps to the young of most pinnulate crinoids. 



There is no proof, nor is it at all probable, that the arms branched 

 again. We may therefore consider the adjacent arm-fragment 

 (Fig, 1), and the other fragments alluded to, as composed of secundi- 

 brachs, and may describe them here. 



The adjacent arm-fragment (Fig. 1) consists of ten brachials, 

 disposed in a curve with a chord of 3-25 mm. Five of these seem 

 to show traces of pinnules, and the alternating five doubtless bore 



