KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 25. N:0 2. 69 



which the main body stånds ont from the colunin at an angle of (50°, but add tliat »no 

 specimen shows the calvx in an ereet position . It is therefore donbtful whether the ra- 

 dials ever nioved so far from the base as Ringueberg's fig. 4 b indicates: in some speci- 

 mens the posterior and right anterior basals have a peculiar bevelled outcr edge (Pl. III, 

 fig. 89), which would pennit of eonsiderable motion without great separation of the plates. 

 In any ease, seeing that the upward motion of the other parts of the crown was produced 

 by nmscles, it is reasonable to suppose that the fosssa at the artieulation of the radials 

 and basals were for nmscles and not for ligament; when three radials took part in the 

 artieulation each had a separate muscle, and the nmscles were usually separated by little 

 projections of stereom. On this supposition there is no necessity for the existence of 

 muscles inside the cup, since the downward motion would be produced by the simple 

 action of gravity. If, however, any interna] nmscles or ligaments were present in Cnlrai- 

 crinus, it would appear, from the evidence of some Dudley specimens, that they were 

 attached immediately beneath the external articular surface, and that they did not occupy 

 so large a part of the basals and radials as in Ringuebergs tigures. 



3. Supplementary plates. In his description of Euchirocrinus. (olim Cremacrinus) 

 punctatus, Mr. Ulricii described »a large number of small and irregularly distributed plates» 

 eovering the hinge-line; these plates he supposed to be developed in an integument eovering 

 the hinge. This interesting strueture was not reniarkecl on by Messrs Wachsmuth and Sprin- 

 ger, and Mr. W. \l. Billings only noticed it to say that the plates were absent from his 

 specinien of Castocrinus furdllatus. Dr. Ringueberg, in his description of Euchirocrinus clvry- 

 salis (op. cit. p. 400) savs, »Faint traces of the integument uniting the two outer margins of the 

 grooves and eovering the elastic ligaments, can be seen. This integument is better show n 

 in some other specimens of I', radiculus, in one of which it is broken iip into small pieces 

 which at first glance have the appearance of 'numerous little plates', such as are ligured 

 by Ulricii in 'Cremacrinus punctatus . In plate X, lig. 13 b, Dr. Ringueberg gives a 

 \ iew of the hinge-line of» »a unique speciraen show ing . . . the articular joint with its 

 connecting ligaments . . . perfectly» »X 5». The drawing, it is to be feared, is not so 

 perfect as the specinien; for botli ligaments and integument appear conspicuous by thcir 

 absence. 



A specinien of Caléeocrinus from the Klinteberg, found not nianv nionths ago by Mr. 

 'i. Liljevall, and described on p. 94 (Plate IV, fig. 126) under the name C. interpres, 

 shows a strueture iindoubtedly homologous with that described by Mr. Ulricii. The whole 

 space of the hinge is tilled witli small plates: in size and shape they are irregular, but 

 as a rule they are wide in the direction of the hinge-line, and are about 0.5 mm. liigh. 

 They are separated from one another above and below by deep spaces from which ii i> 

 difficult to clean the matrix, but laterally they abut closely on one another. The spaces 

 between them are greatest along the middle line of tlie hinge; as the}' approach the radials 

 above and the basals below, the plates are niore closely pressed together, and indeed it is 

 härd to distinguish them from the cup-plates theniselves, especially on the basa! side. 

 These plates are rather darker in appearance than the main cup-plates, i. c. they are 

 niore translucent, which may be caused by greater clensity of strueture. It is exceedingly 

 note-worthy that this same specinien has similar plates in some of the gaping artieulation s 



