FOSSILS OF THE BURLINGTON GROUP. 363 



STKOTOCRIXUS (PHYSETOCRINUS) DILATATUS, M. and W. 



PI. 10, Fig. 6. 



Strotocrinu* (Phygttocrinus) dilatatui, MEEK and WoRTHRX. Proceed. A_ca<l. Nat Sci., Phila., 1869, 

 p. 162. 



BODY rapidly expanding, with nearly straight sides, 

 from the base to the secondary radials, thence spreading 

 more abruptly to the brachial pieces, which are directed 

 out nearly horizontally, and so closely crowded all around 

 as to coine very nearly, or sometimes quite, in contact over 

 the anal and interradial areas. Base about three times as 

 wide as high, not thickened or expanded below, but provi- 

 ded with a large round perforation. First radial pieces 

 comparatively large, generally wider than high, two hep- 

 tagonal and three hexagonal. Second radials only about 

 half as large as the first, some of them quadrangular, and 

 others with one or both of the upper lateral angles a little 

 truncated, so as to make them properly pentagonal or hex- 

 agonal. Third radials larger than the second, wider than 

 long, pentagonal, hexagonal or heptagonal, and supporting 

 on each superior sloping side a secondary radial, each of 

 which gives origin on its outer side to brachial pieces lead- 

 ing to an arm, while on its inner side a tertiary radial gives 

 origin to two arms in all but the two posterior rays, where 

 one or sometimes both bear on one side another axillary 

 piece, making seven or eight arms in, each of these rays, 

 or, in the latter cases, thirty-four arms to the entire series. 



First anal piece as large as the largest first radial pieces, 

 and bearing above two heptagonal or octagonal pieces of 

 near its own size in the second range, with three smaller 

 pieces in the third range, and two or three minute pieces 

 over these, one of which is wedged in between the brachial 

 pieces above. First interradial pieces generally larger than 

 the second radials, heptagonal or octagonal, and surmounted 

 by two smaller pieces in the second range, over which we 

 usually see one or two small pieces wedged up between the 



