170 F. A. BATHER, CRINOIDEA OF GOTLAND. 



tuberculate or with raised articular margins. They are almost at right angles to the long 

 ;ixis of the calyx. 



Illir 1 or 2, rarely, if ever, more. They are similar in shape and ornament to IBr. 



IIIBr from 1 to 3, rarely, if ever, more. Illax expands above, but the other os- 

 sicles are not constricted. Ornament as before. 



In the remaining series the ossicles are a little longer in proportion to their width, 

 and more are found in a series. They are still tuberculate, and in some specimens are 

 ridged on the articular margins, but more often are simply rounded (hg. 343). 



Anal struetures: x is hexagonal and supports two plates (fig. 341). 



No specimen shows all the immediately ensuing plates but there is no reason to 

 suppose that they differed from those of other Gissocrini. There were at any råte two 

 lateral plates, and there must have been as usual one proximal median plate between 

 them. The Ventral Sac itself is composed of several alt ernating series of hexag< mal plates, 

 which are rather prominent and have slightly folded edges (fig. 348). The sac attained 

 a length of at least 22 mm. in one specimen. In its distal region the plates present a 

 less regular appearance, and tend to run in transverse folds. The chief peculiarity of the 

 sac is its position; it appears to pass out almost horizontally from the calyx, and in one 

 specimen actually appears to be pendent, lying alongside of the stem (ef. fig. 342). 



The Tegmen shows 4 deltoids and a madreporite. All these five plates are verv 

 similar in shape and position, and the food-grooves pass över their edges to the actinal 

 centre (fig. 339). That in the posterior interradius, however, the madreporite, appears 

 rugose and of darker colour than the others (fig. 340). The extremely lateral situation 

 of the ventral sac causes less departure from pentamerous symmetry in the posterior 

 interradius of the tegmen than is usually the case. The ambulacrals are clearly seen 

 passing över the edges of the deltoids and the madreporite. Those in the centre are 

 larger, but can hardly be thought to represent orals as they are certainly not interradial 

 in position. 



The Stem in one specimen (that in which the sac is preserved) has a length of 

 at least 24 mm., including the root (fig. 342). The average width of the stem in this 

 specimen is 5 mm. It is normally composed of rather low ossicles alternating in height, 

 the higher ones projecting in rough ridges. In the distal part of the stem in this specimen 

 there is considerable irregularity, and the ossicles are broken up by longitudinal or oblique 

 sutures (fig. 347). Whether this is a pathological or senile development, or whether it 

 is an original structure is uncertain. The Root forms an incrustation. 



Notes on Angelin's figures: 



Tab. XVI, fig. 1. The ventral sac is obviously broken off just above the proximal 

 median plate. The specimen is unknown. 



Tab. XVI, figs. 2 and 3 show the shape and ornament of the brachials very well, 

 but they are rather lower than is usual in the species. 



Tal). XXVI, fig. 1 is a very correct drawing of the specimen. 



