ler, lrfedens de svagt afnindede Prerastaaenheder paa Pen- 

 tagonalen falder sammen med Længdesommene mellem de 

 Iste Radialer. De sammensmeltede Basaler danne for- 

 neden en rund, lidt excaveret Flade, der ved en Søm for- 

 ener dem med Stilkens øverste Led. 



Det første Radial er noget forskjelligt i Størrelse efter 

 Hovedets Længde; paa det Exemplar, der er 110""" langt, 

 er det 1.0"? langt. 0.9""" bredt forneden, Tab. II, Fig. 1 a, 

 2 a. Det er kiledannet. Dets dorsale Flade er paa Midten 

 convex, lidt afplaneret til Siderne, Tab. II, Fig. 2 a. Den 

 ventrale Flade er paa den nederste Halvdel convex, paa 

 den øverste findes en dyb Fure, som fremkommer derved, 

 at den øverste Leddeflades Rand her er spaltet, Tab. I, 

 Fig. 8 a. Sidefladerne ere smale, yderst svagt concave, 

 næsten plane, og der, hvor de støde til den dorsale Flade, 

 dannes en temmelig skarp Kant. Saavel denne som selve 

 Sidefladen er sammenvoxet med det tilstødende Side-Ra- 

 diale, hvorved fremkommer det egentlige Bæger (Calyx), 

 som er meget lidet, og paa hvis udvendige Side der er 5 

 yderst fine Linier. som betegne Sømmene for Sammenvox- 

 ningen, Tab. I, Fig. 2 i. Tab. II. Fig. 1 b. 



Den øverste (distale) Flade er ved en næsten trekan- 

 tet, glat, hvælvet Kam. som indtager Størstedelen af Fla- 

 dens Tvervidde. egentlig delt i to Dele, en ventral og en 

 dorsal. Den dorsale Del optages næsten ganske af en 

 halvrund Fordybningv der tilkjendegiver sig paa den dorsale 

 Flades ovre Rand som en halvmaaneformig Indskjæring, 

 Tab. II, Fig. 1 c, 2 b, og paa den ventrale Del sees For- 

 længelsen af den paa den ventrale Flade omtalte Fure, ved 

 hvis Sider Muskler fæste sig. Paa hver Side af Kammen, 

 mellem denne og den distale Flades afrundede Rand, er 

 en lang Fure, som har en skjæv Retning udenfra indad, 

 ovenfra nedad, der støder sammen med Midtfuren. og som 

 tjener til Insertion for stærke, senede Baand. Den afrun- 

 dede, glatte Rand, der mod Dorsalfladen er afskaaren ved 

 det halvmaaneformige Indsnit og mod Ventraltladen ved 

 Furen, danner i Forening med den glatte, hvælvede Kam, 

 den egentlige Artikulationsflade. Imellem Kammen og den 

 halvrunde Fordybning, lige i Centrum, findes et lidet, 

 rundt Hul til Grjennemgang for Centralstrængens Forgre- 

 ning. Den underste (proximale) Flade er lidt ophøiet paa 

 Midten, skraaner af til Siderne og er fast forenet ved en 

 Som til to Basaler. 



Det andet Radiale er lidt længere, bredere, noget 

 tykkere og nærmer sig næsten Firkanten; det er 1.2""" 

 langt, 1.0™" bredt fo roven og 0.9""" bredt forneden, Tab. Il, 

 Fig. 1 d, 2c; dets dorsale Flade er lidt eoneav ovenfra nedad, 

 paa Midten convex fra den ene Side til den anden, men 

 bliver til Siderne lidt concav. Tab. II, Fig. 2 d. Den ven- 

 trale Flade har paa Midten et convex Fiemspring, hvorpaa 

 iagttages en Længdefure, Tab. I. Fig. 9. Sidefladerne ere 

 svagt convexe, have en skråa Retning udenfra indad, ere 

 lidt bredere end de paa første Radiale og gaa næsten 



(Pl. I, figs. 3-m, 7) in whose concavities the articular sur- 

 faces for the Ist radials are found. while the faintly rounded 

 projections on the pentagon coincide witb the longitudinal 

 seams between the Ist radials. The coalesced basalia form 

 at the bottom a round, slightly excavated surface, which 

 by a seam unites them to the uppermost joint of the stalk. 



The first radial is somewhat variable in size. according 

 to the length of the head; in the specimen that is 140""" 

 in length, it is 1"'"' long. and 0.9""" broad at the bottom 

 (Pl. 2, figs. 1 a, 2 a). It is cuneiform. Its dorsal surface 

 is convex in the middle, slightly planed off towards the 

 sides (Pl. II. fig. 2 a). The ventral surface is convex in 

 the lowest half part, in the uppermost half part a deep 

 groove appears, which is produced by the margin of the 

 uppermost articular surface being here fissured (Pl. I, fig. 

 8 a). The lateral surfaces are narrow, extremely faintly 

 concave, almost plane, and, at the point where thev unite 

 to the dorsal surface a pretty sharp edge is formed. Both 

 that. as well as the lateral surface itself are concreted with 

 the adjacent lateral radials, thereby producing tlie cup- 

 proper (the calyx), which is very small, and upon whose 

 exterior side there are 5 extremely fine lines indicating 

 the seams of the eoncretion (Pl. I, fig. 2 i. Pl. II, fig. 1 b). 



The uppermost (distal) surface is really divided by 

 an almost triangular, smooth, arcuate ridge that occupies 

 the greater part of the transversal width of the surface, 

 into two portions, a ventral and a dorsal. The dorsal 

 portion is almost entirely occupied by a semi-circular cavity, 

 which makes itself apparent on the superior margin of the 

 dorsal surface as a peltiform concavity (Pl. II. figs. 1 c, 

 2b); and on the ventral portion is seen the prolongation 

 of the groove spoken of as appearing on the ventral sur- 

 face, upon whose sides muscles secure themselves. On each 

 side of the ridge, between it and the rounded margin of 

 the distal surface, there is a long groove, having an oblique 

 direction from outside inwards and from upwards downwards, 

 which unites with the medial groove and serves as the 

 insertion for strong, sinuous bands. The rounded, smooth 

 margin, which towards the dorsal surface is transected by 

 the peltiform incision and towards the ventral surface by 

 the groove, forms, in connection with the smooth arcuate 

 ridge, the real articular surface. Between the ridge and 

 the semi-circular cavity, exactly in the centre, there is 

 visible a small round hole for the passage of the ramifi- 

 cation of the central cord. The lowest (proximal) surface 

 is a little elevated in the middle and slopes off to the 

 sides; it is firmly united by a seam to two basalia. 



The second radial is a little longer, broader. some- 

 what thicker, and almost approaches a quadrangle in form ; 

 it is 1.2""" long, L.0"™ broad at the top and 0.9""" broad 

 at the bottom (Pl. II, figs. 1 d, 2 c); its dorsal surface is 

 slightly concave. from above downwards, in the middle con- 

 vex. from the one side to the other, but at the sides be- 

 comes slightly concave (Pl. II, fig. 2 d). The ventral sur- 

 face has a convex projection in the middle on which a 

 longitudinal groove is observed (Pl. I, fig. 9). The lateral 

 surfaces are faintly convex. have an oblique direction from 



