408 Mr. F. A. Bather on British Fossil Crinoids : 



The Stem. — The presence of Radial Sutures has not, so far 

 as I am aware, hitherto been noticed in this genus ; thus one 

 more is added to the gradually increasing number of early 

 forms in which the stem is so divided. These sutures are, as 

 a rule, more observable in the young, and they are more 

 marked in the distal region of the stem. These two facts 



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STRUCTURE IN BOTRYOCRINUS. 



Fig. 1. The anal area of B. decadactylus ; mainly from evidence of E 1419, 



B. M. (X 3.) 

 Fig. 2. From the proximal part of the Ventral Sac of a large specimen of 



B. cucurbitaceus, from Bursvik, Gotland, in Riksmuseum, 



Stockholm. To show the folding, without perforation, of the 



plates. The distal end of the sac is beyond the left of the 



drawing. ( X 6.) 

 Fig. 3. Part of the ventral sac, as seen from the back, of a specimen of 



B. ramosissimus in Riksmuseum, Stockholm, which was figured 



in Angelin's ' Iconographia,' Tab. xxiii. fig. 14. (X 3.) 

 Fig. 4. Ventral surface of arm of a large specimen of B. ramosissimus, 



from Follingbo, Gotland, in Riksmuseum, Stockholm. To show 



small, irregular covering-plates. ( x -£.) 

 Fig. 5. Distal part of stem of B. decadactylus, E 1412, B. M. To show 



irregularity of pentameres. (X 12.) 

 Fig. 6. Root of B. decadactylus, E 1412, B. M. ( x 3.) 



imply that the sutures are, so far as the present stage of 

 evolution is concerned, primitive structures. The same, it 



