KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 25. N:0 2. 33 



articular facet (Pl. I, fig. 18) has the triangulär muscular depressions on the inner side 

 of the fulcral ridge more marked than in P. pilula. 



The calyeal cavity is irregularly pentagonal above, but lower down, owing to the 

 projeetion of the two larger radials and the radianal, it becomes irregularly trigonal (Pl. I, 

 fig. 17). This projeetion of the plates towards the base of the cavity may be compared 

 with that shown in P. pilula (Pl. I, tig. 11). 



Arms unknown. 



Anal struetures: R' curves inwards to form part of the basal concavity; its apex 

 niav or may not be produced in a long process (c/V. Ang. Iconogr. Tab. IV, fig. 2, 2 a). 



Anal x and tube unknown. 



Teginen and Stem unknown. 



'O ' 



Notes on Angelin's figures: 



Tab. IV fig. 2 is seen from the right posterior interradius, and is therefore a 

 different specimen from fig. 2 a, which is seen on the same aspect. 



Tab. IV fig. 2 c is redrawn in Pl. I tig. 17 with more accuracy. 



Tal). IV fig. 2 d seems unnatural, but, in the absence of the original, criticism is 

 impossible. 



Tab. IV fig. 2 b, if it represents this species, is absolutely incorrect and ineomprehen- 

 sible; it seems to me that it may be intended for a drawing of a small sub-pentagonal 

 cup, composed of 5 B and 5 R, that was among specimens of P. pilula and P. ollula 

 from Petesvik. 



Localities: Burge sawmill in Fardhem (c), 'Canal' on Wisne Myr (c), Hemse (c), 

 Petesvik (c), Linde Klint (f), Klinteberg (f). Not known outside Gotland. 



Pisoorinus pocillum. 



(Plate I, figs. 20—23.) 

 1878. Angelin, Iconographia, p. 21, Tab. IV, fig. 3, 3 a. 



Emended diagnosis. 



Cup elongate, conical; sub-triangular in section, the angles running down the middle 

 of each of the three large plates, and the sides between being almost flat. BB elongate, 

 turned almost at right angles to stem articulation. Ant. R and 1. post. R and R' elongate; 

 1. ant. R, r. post. R, r. ant. R wide and not elongate. Radial piocesses verv thin except in 

 post. IR. Arm ossicles long, triangulär in section. 



Description. 



Dorsal cup: In the shape of the cup this species approaches such forms of Tria- 

 crinus as T. elongatus, Follm., and T. ältas, Mlll. It is readily distinguished from the 

 forms of P. pilula that resemble it most closely by the great height of the basals, and 



K. Sv. Vet. Akud. Handl. Band. 25. N:o 2. 5 



