umærkeligt over i den ventrale Flade. Der, hvor Sidefladerne 

 støde til den dorsale Flade, er en afrundet, fri Rand, som 

 er bøiet lidt opad og udåd, hvorved der fremkommer en 

 Spalte imellem den anden Radialrækkes enkelte Stykker, 

 saa at Skivens Perisom kommer tilsyne, Tab. II, Fig. 1. 

 Den underste Flade, der er en fuldstændig Leddeflade, 

 svarer til den øverste Flade paa første Radiale, hvormed 

 den artikulerer, Tab. I, Fig. 2k; Tab. II, Fig. le, 2b. 

 Den øverste Flade derimod har paa Midten en konvex 

 Fremstaaenhed. er til Siderne næsten plan og er ved en 

 organisk Masse fast forenet til det tredie Radiale, hvorved 

 fremkommer et Syzygium, Tab. II, Fig. le, 2 e. 



Det tredie Radiale (Radiale axillare) er bredere og 

 meget kortere, end andet Radiale, 1..")""" langt, 2.0""» bredt 

 foroven, 1""" bredt forneden, Tab. II, Fig. i f, 2 f. Den 

 dorsale og ventrale Flade har omtrent samme Form som 

 andet Radiale, Tab. I. Fig. 10. Den underste Flade 

 svarer til andet Radiales overste Flade. hvormed den er fast 

 forenet. Den øverste Flade har paa Midten en konvex 

 Forhoining, der indtager Fladens korteste Axe, og som 

 paa den dorsale Sides overste Rand tilkjendegiver sig med 

 en konisk Fremstaaenhed, Tab. II, Fig. 1 g, 2 g. Paa hver 

 Side af denne Forhoining er en halvrund Fordybning. Tal). 

 I, Fig. 10 c, der tjener til Befæstning for senede Baand 

 og Muskelfibre, og udenfor denne Fordybning er den egent- 

 lige Leddeflade for Armen. Imellem Fordybningen og 

 denne Leddeflade er der en rund Aabning til Grjennemgang 

 for en Gren af Centralstrængen. Paa den øverste Flade 

 af tredie Radiale er der altsaa to virkelige Artikulations- 

 flader. 



Fra Radiale axillare udgaa 2 Arme, der have for- 

 skjellig Længde efter Individets Størrelse og Alder. Paa 

 det største Hoved (Krone) vare Armene indtil 30""" lange. 

 Hver Arm var sammensat af 55 enkelte Led, foruden det 

 yderste Led, som ender i en liden, konisk Spids. De 10 

 nederste Led ere blottede for Pinnuler og ere ordnede paa 

 følgende Maade. Det første og andet Led er sammen- 

 voxet ved en Søm, hvorved et Slags Syzygium fremkom- 

 mer; mellem andet og tredie Led er der en virkelig Arti- 

 kulation, ligesaa mellem tredie og fjerde; men mellem 

 fjerde og femte er igjen et Syzygium; saa kommer mellem 

 femte og sjette og mellem sjette og syvende en virkelig 

 Artikulation, mellem syvende og ottende et Syzygium, og 

 endelig mellem ottende og niende, samt mellem niende og 

 tiende virkelige Artikulationer. Der er altsaa syv virkelige, 

 bevægelige Led, naar Leddet mellem tredie Radiale og 

 første Braehiale medregnes, og tre med Somme sammen- 

 voxede og ubevægelige Led. Dette gjælder gamle Individer, 

 Tab. I, Fig. 1; Tab. II, Fig. 2 h, i. Hos yngre Individer 

 ere Syzygierne mindre fremtrædende, og hos ganske unge, 

 lidet udviklede, existere de ikke; hos dem er der Artikula- 

 tioner overalt, Tab. I, fig. 2. 



outwards inwards, are a little broader than those of the 

 first, radial, and pass almost imperceptibly over into the 

 ventral surface. In the situation where the lateral surfaces 

 unite to the dorsal surface there is a rounded iree margin, 

 which is curved a little upvvards and outwards, producing 

 thereby a fissure between the individual portions of the 

 second radial series, so that the perisome of the disc be- 

 comes visible (Pl. II, fig. 1). The lowest surface. which 

 is a perfect articular surface, corresponds to the uppermost 

 surface of the first radial, with which it articulates (Pl. I, 

 fig. 2 k, Pl. II, figs. 1 c, 2 b). The uppermost surface, on 

 the contrary, has a convex projection in the middle. is 

 almost plane at the sides, and is firmly united by an or- 

 ganic mass to the third radial, producing thus a syzygium 

 (Pl. II, figs. 1 e, 2 e). 



The third radial (radiale axillare) is broader and 

 much shorter than the second radial; it is 1.5""" long, 2""" 

 broad at the top and 1""", broad at the bottom (Pl. II, 

 figs. 1 f, 2 f). The dorsal and ventral surfaces, have nearlv 

 the same shape as those of the second radial (Pl. I, fig. 

 10). The lowest surface corresponds to the uppermost 

 surface of the second radial, to which it is firmly united. 

 The uppermost surfare lias a convex projection in the 

 middle, which occupies the shortest axis of the surface and 

 evinces itself by a conical projection on the uppermost 

 margin of the dorsal side (Pl. II, figs. 1 g, 2 g). Upon 

 each side of this projection there is a semi-circular cavity 

 (Pl. 1, fig. 10c), which serves for the attachment of sinuous 

 bands and muscular fibres, and outside this cavity is the 

 real articular surface for the arm. Between the cavity 

 and this articular surface there is a round aperture for 

 the passage ot a branch of the central cord. On the up- 

 permost surface of the third radial there are, therefore, two 

 real articular surfaces. 



From the radiale axillare 2 arms issue, of variable 

 length according to the size and age of the individual. On 

 the largest head (crown) the arms were as much as 30""° 

 jn length. Each arm was composed of 55 individual joints, 

 besides the outermost joint, which terminates in a small 

 conical point. The 10 lowest joints are devoid of pinnules 

 and are arranged in the following manner. The first and 

 second joints are concreted by a seam, which produces a 

 kind of syzygium ; between the second and third joints 

 there is a real articulation, likewise between the third and 

 fourth; but between the fourth and fifth there again comes 

 a syzygium ; then there comes between the fifth and sixth. 

 and between the sixth and seventh, a real articulation; be- 

 tween the seventh and eighth a syzygium; and, finally, be- 

 tween the eighth and ninth, and also between the ninth 

 and tenth. real articulations. There are thus seven real, 

 flexible joints, when the joint between the third radial and 

 first brachial is included, and three, concreted by seams 

 and inflexible joints. This refers to old individuals 

 (Pl. I, fig. 1. Pl. II, fig. 2 h, i). In younger individuals 

 the syzygia are less prominent, and in perfectly young, little 

 developed specimens they do not exist; in them there are 

 articulations everywhere (Pl. I, fig. 2). 



