KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 25. X:<> 2. 147 



branching are coneerned. Its plates are tumid, except on the posterior side, where they 

 have been much rubbed down, thus produeing an apparent resemblance. The covering- 

 plates are no where exposed, so that it has not been possible to decide the point definitely. 



Description. 



Dorsal eup shaped like a pudding-bowl, with almost straight sides spreading out 

 straight from the stem, at an angle of 30 — 40° to the vertical axis. Sometimes, indced, 

 there is a slight curvature of the sides; but this is never so marked as in C. longimanus. 

 The plates of the cup are smooth and plane, being only depressed very slightly towards 

 the sutures. In specimen b there are traces of a slight shagreen ornament on the cup- 

 plates, as well as on the arm-ossicles. This ornament, however, is so exactly the same 

 as that on the arms of all typical specimens of the present species that it cannot be re- 

 garded as a diagnostic character. In all other respects specimen b resembles C. ramosus, so 

 that the name C. alutac&us is not required for it. Specimen d was separated by Angelin as 

 C. zonatus, owing to the concentrically ridged ornament of the basals. Concentric ridges 

 crossed by radiating ridges are also seen on the radials and, to a less extent, on the 

 infrabasals. Such an ornament, however, must be regarded as merely a character of age; 

 it is much like that of C visbycensis var. monilifer, and is seen, though to a less extent, 

 in an okl specimen of C. longimanus. The cup-plates in »C. zonatus-» are, it is true, higher 

 in proportion than in normal specimens of C. ramosus, and thus the specimen resembles 

 C. longimanus ; on the other hand the arm-ossicles and covering-plates are so much more 

 like those of C. ramosus that it seems advisable to consider specimen d as a gerontic 

 variety of this species. 



IBB 5; pentagonal; very low; not projecting from the stem as in C. longimanus. 

 Measurements — in a, height 2 mm., width below 5 mm., width above 5.4 mm.; in g, 

 height 4 mm., width below 6.75 mm., width above 7 mm.; in d, height 9 mm.(?), width 

 below 11.25 mm.(?), width above 13 mm. 



BB o. Four are hexagonal; with the two luwer sides forming a very wide angle, 

 sometimes a gentle curve, or almost a straight line. Measurements — in a, height 6.8 

 mm., width below 6.8 mm., width above 8.25 mm.; in g, height 8.5 mm., width below 9 

 min., width above 10 mm.; in d, height 16 mm., width below and above 13.25 mm. 

 Post. B is heptagonal, of the usual shape, and of much the same proportions as in C. 

 longimanus, but a trifle wider. 



RR 5; pentagonal or shield-shaped, sloping in above. There is no constant differ- 

 ence between these and those of C. longimanus. Measurements — in a, height 9.5 mm., 

 height to bottom of facet 6.5 mm., width below 10.5 mm., greatest width 12 mm., in g, 

 height 11 mm., to bottom of facet 7 mm., width below 11 mm., greatest width 11.5 

 mm.; in d, height 15.5 mm., to bottom of facet 10.5 mm., width below 13.5 mm., width 

 above (which is greatest) 14.5 mm. Articular facet elliptical, with a wide notch above, 

 and a distinct axial canal placed as in C. longimanus. Greatest width, in a, 5.25 mm.; 

 in g, 5 mm.; in d, 5.5 mm. The inner side of a radial, showing the entry of the ven trål 

 groove and axial canal, is drawn in lig. 257. 



