KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 25. N!0 2. 51 



ossicles rapidly decrease in length, and the whole cirrus rapidly tapers (fig. 51). The 

 backs of the cirrals are rounded, their sides compressed. Their axial canal, where it 

 leaves the stem, is elongate (figs. 55, 57). 



The outer lateral sutures are rather closer together than in H. Fletcheri, being 

 placed at rather more than \' 3 of the distance between the median outer line and the 

 origin of the cirri. Between these sutures the stem is raised into a rounded ridge with 

 a flat back, which however is not very obvious (figs. 54, 58). 



This species was not figur ed by Angelin. 



Localitv in Gotland: Follingbo (f). Commoner at Dudley. 



Herpetocrinus flabellicirrus, n. sp. 



(Plate II, figs. 64—77.) 



Diagnosis. 



Cirri confined to region 6, where they are arranged in alternating fan-like groups, 

 two cirri springing from each ossicle: proximal cirrals flat and elongate; distal ones wide 

 and rounded. Outer median sutures clear; lateral sutures less clear. Coil rather close. 



This species is founded on seven specimens of stem, lettered a — g. 



Description. 



The greater part of the stem, corresponding to the 5 proximal regions of H. Flet- 

 cheri, appears to be devoid of cirri. 



The change from region 2 to 3 is sudden. 



In regions 4 and 5 the columnals are regular, equal, shaped like those of H. Ammo- 

 nis, but less excavate on the inner curve, and sometimes quite flat on that side. 



Region 6 has largc cirri arranged in a very peculiar mariner. Each columnal bears 

 two cirri, one on either side. The cirri of each side of the stem are arranged in groups 

 of about a dozen. In each group the line of origin of the cirri, which appears like a 

 suture-line between cirri and stem, instead of curving with the stem, is straight or even 

 curved in the opposite direction; consequently it gradually passes from the inner to the 

 outer side of the stem; and this, at all events when the stem is coiled, causes the cirri 

 to have an upward trend. Further, since the cirri increase in thickness towards their 

 middle region, this makes each group form a spread fan. Hence when the stem is coiled, 

 and even, to a less extent, when uncoiled, the cirri of each distal group lie över those 

 of the succeeding proximal group: in this way 4 groups of cirri may lie one över the 

 other (Pl. II, fig. 64). In conformity with this arrangement the distal cirri of each group 

 are much smaller than the proximal ones: the cirri of each group are graded in size, but 

 the råte of increase is higher at the proximal end. The cirrus-groups do not coincide on 

 opposite sides of the stem but appear to alternate. 



A cirrus in one specimen attains a length of 20 min. and is by no means complete; 

 it is about the middle of a group, in a specimen of medium size (Pl. II, fig. 66). In 



