KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 25. N:0 2. 49 



Of this species a single speeimen, consisting of a coiled stem, has quite recently been 

 found in Gotland. 



Description of the speeimen. 



The stem is closely coiled in the proximal part, but uncoiled clistally, so that the 

 longest diameter of the total coil is 25 mm., and the shortest is 16 mm. (fig. 50). The 

 speeimen is considerably flattened so that the sections of the columnals are probably some- 

 what distorted (fig. 52 a). 



In the distal region of the stem about 8 ossicles go to 5 mm., and, so far as can 

 be seen, the height of the ossicles lessens very slightly towards the proximal region. 

 The greatest width of a columnal in the distal region is 3.25 mm. (fig. 52 a), while at 

 the point marked b in fig. 50, the width is 3 mm. In the distal region, however, the 

 section is sub-triangular, while higher up it is sub-crescentic; thus the mean width of a 

 colnmnal is less in the distal region. This difference is more marked in some specimens 

 of H. Ammonis, but may be partly due to distortion. All the columnals visible are 

 cirriferous, and, in the more closely coiled regions of the stem, their height is slightly 

 less on the inner curve. 



The cirri, so far as seen, are regularly paired on each ossicle. They attain at most 

 a length of 9 mm., and are composed of about 7 ossicles (fig. 51). The width of each 

 cirrus-articulation is equal to the height of the columnal on whieh it occurs. The proxi- 

 mal cirral is at most 0.8 mm. long: subsequent ossicles rapidly decrease in length, and the 

 whole cirrus rapidly tapers. The cirri are flattened and closely apposed, so that the 

 section of a cirral is sub-quadrangular and elongate, with a correspondingly elongate axial 

 canal (fig. 53). 



The outer lateral sutures are clear, and lie in a very slight depression. They occupy 

 the same relative position as in H. ffletcheri. 



This species was not figured by Angelin. 



Locality in Gotland: Tofta soke; precise locality not known. The chief fossili- 

 ferous beds in Tofta occur on the shore and are c. The species al so occurs in the 

 Niagara Beds of N. America. 



Herpetocrinus Ammonis, n. sp. 



(Plate II, figs. 54—63.) 

 Diagnosis. 



Cirri either paired on alternate ossicles, or alternating, one on each ossicle; eonfined 

 to regions 4, 5 and 6; short: cirrals longer than wide in proximal part of cirrus, squarish 

 in section. Outer lateral sutures clear; median sutures not seen. Coil very close. 



K. Sv. Vet. Akad. Handl. Band. 25. N:o 2. 7 



