110 F. A. BATHER, CRINOIDEA OF GOTLAND. 



IIBr usually 2 or 3, rarely 1, 4 or 5. Tliey are rather higher than, and about half 

 the width of, the priraibrachs. 



III Br 2, 3, 4, or 5; less wide and rather deeper in proportion. 



The succeeding brachials are of two or three series, and are as a rule coiled inwarda 

 över the tegmen around the anal tube. 



Different specimens present the following variations in arra-structure. The primi- 

 brachs and secundibrachs sornetimes extend almost at right angles to the cup-wall, as in 

 specimens c and d; sornetimes they pass up more in a line with the cup-wall, as in spe- 

 cimens a, b and e. The brachials are sornetimes low and wide as in Forbesocrinus, and 

 this is the case in specimens e and g, in which the arms have a low appearance. .Sornetimes 

 the arms are more extended, owing partly to the greater number of ossicles in a series, 

 partly to their less width, as in specimens a and f. The extended appearance is enhanced 

 by the rather less coiled state of those arms. If we enquire in which direction evolution 

 is proceeding, it appears clear from a comparison with the earlier E. obconicus that the 

 tendency is towards lower ossicles, diminution of number in a series, and greater coiling. 

 The gain to the aninial of this change is less obvious. 



Anal structures: Anal x is hexagonal. It rests on 1. post. B, R' and 1. post. R; 

 by one side it abuts on the third anal plate between it and r. post. R, while on its two 

 upper sides it supports two other anal pla.tes. 



The anal tube is composed of hexagonal plates, more or less massive. These plates 

 may be flat and elongate, 4 mm. by 2.5 mm., and not very thick, so that the lumen is 

 moderately large; e. g. specimens a and b; or they may be swollen and slightly wider, 

 4 mm. by 3 mm., and rather thicker, so that the lumen is smaller in proportion; e. g. 

 specimens e, f and h. These plates are apparently arranged in alternating circlets of 5, 

 or distally of 4. At the proximal end, the tube is large, and wider than deep; thus in 

 specimen c it is 9.75 mm. by 7.75 mm., with a lumen of 4 mm. by 3 mm. Higher up, 

 the tube narrows; thus in specimen a it is 4 mm. by 4 mm., with a lumen of 2 mm. 

 by 2 mm.; while in specimen i the distal diameter is 6 ram., the diameter of the lumen 

 2.25 mm. Although therefore the tube outwardly resembles that of an Actinocrinus, it 

 will be observed that the lumen, even at its narrowest, is proportionally wider than in 

 that genus. The tube projects above the coiled arms, but how far cannot be ascertained. 

 In spcciiii<'ii ,i it is broken off at 9a mm. above the tegmen. 



It has been stated by Messrs. Wachsmuth and Springer (op. cit. ult., p. 358) that 

 the ventral tube of this species is »profusely perforated». I have most carefully examined 

 the plates with a view to discovering any perforations, whether in the substance of the 

 plates thcmselves or along the sutures between them, but I have as vet quite failed to 

 distinguish any, and perhaps Prof. Lindström will pennit me to say that he too could 

 see none. No previous observer has ever described such structures, and Messrs ^ aciis- 

 mutii and Springer themselves said in their Revision (I, 143) »Pores have not been ob- 

 served . Mr. W. R. Billings neither mentioned nor indicated pores in E. obconicus. 



The Tegmen is rather massive (Text-hgures 14, 15 and Pl. V, fig. 153). In each 

 interradius excepl the posterior is a large rhomboidal or heart-shaped ])late, which may 

 be called a deltoid. The four deltoids abut on the upper ends of the radials, and, except 



