122 E. A. RATHER, CRIXOIDEA OF GOTLAND. 



of plain hexagonal plates, lying between similar rows folded on their outer sides. The 

 folding sets in very gradually, hut becomes, in the distal region, verv pronounced. All 

 plates on the sides of the sac are ridged and folded as usual in the genus; hut a.nteriorly 

 is a similar row of plain hexagonal plates. The sac is at tirst nnrrow, hu1 ;is it ascends 

 increases slightly in width. At tirst it bends in an anterior direction, then distally curvea 

 round on itself in the same plane, just as it does in B. ramosissimus, with this difference, 

 that in the angle of the curve the plates appear to have grown together. This slight coil 

 of the sac is by no means so remarkable as it appears at first sight; the inner passage 

 is merely bent round in a semicircle and did not return on itself as, from the evidence 

 of Angeun's tigures alone, Wachsmuth and Springer seem to have supposed. The walls 

 of the swollen end of the sac were quite thin. I have previouslv (op. dt., p. 406) alluded 

 to the opinion that slits or pores were present in this sac, and I have stated my inability to 

 deinonstrate any such. (Text-tig. 17(2), and Pl. VI, tig. 190). Since puhlishing tliose observa- 

 tions I have again had the opportunity of exainining the specimens, and have nothing to alter. 



There seems to be an anal opening surrounded by small plates, just below the coil, 

 on the posterior side (tig. 183). 



The St em is pentagonal, with angles interradial. The portions preserved are com- 

 posed of alternately thick and thin ossicles; some of these stånd out more than others, 

 and the most proximal 3 or 4 ossicles are quite thin. The axial canal is small and penta- 

 gonal, with angles radial. The articular surfaces show slight radiating striae. No longi- 

 tudinal sutures are visible (tigs. 181, 193). 



Remarks on Angelins figures. 



Tah. IV, tig. 9: The Ventral Sac is partly restored in the angle of the curved por- 

 tion. The Stem, as noted by Angelin, is »perverse delineata». In other respects the figure 

 is fairly correct. The true length of the specimen is 34 mm., of which the stem occu- 

 pies 10 mm. The figure is therefore enlarged nearly 3 times. 



Tal). XVI, tig. 5: The specimen cannot be found. 



Localities. a, b and c are from Bursvik, in sandy matrix, bed c. d, e, f and g are 

 from the west side of Wamlingbo quarry, in a sandy shale (c). Not known out of Gotland. 



Streptocrinus. 



1878, Ophioerinufi Angelix, Iconographia, p. 24, non Salter, 1856, Charlesworth, 1865, nrc 



Semper, 1868. 

 1879 Ophiocrinus Wachsmuth and Sprixger, Revision I, 97, Proc. Acad. Nat. Sci. Philadelphia, 



1879, p. 320. 

 1886 Streptocrinus Wachsmuth and Sr-RiNGER, Revision 111 224, Proc. Acad. Nat. Sci. Philadelphia, 



1886, p. 148. 



The sole point in Angelin's diagnosis by which this genus was distinguished from 

 Cyathocrinus lay in the words Hubus analis .... cochleatim convolutus». Messrs Wachs- 

 muth and Springer in their description based on Angelin's figures (Revision I, 97), while 

 they laid stress on this character, also upheld the genus on accouht of iis pendenl arma 



