Dr. F. A. Bather — On Psalidocrinus reiinesi. 349 



The lower half of the patina of A was described by Dr. Eemes 

 (1912, p. 167) as ' cylindrisch ', a phrase that he has permitted me to 

 modify in his present description. Even this, however, does not go 

 far enough to Justify the statement that B resembles A " in external 

 form". So far as measurements are at all possible, the actual facts 

 are these : in the lower part of the patina the sides approach at an 

 angle of '45° in A, of 80° iu B ; in the upper half of the patina the 

 sides approach at an angle of 105° in A, of 108° in B. Therefore the 

 lower part meets the upper part at an angle of 145° in A, of 166° in B, 



The view of the patina from below (Text-fig. 2, and Bemes, 1912, 

 pi. iii, fig. 2c) shows a clear difference of surface-modelling. In 

 A the interradial depressions continue from the margin of the patina 

 to the stem-facet ; in B they continue only half-way, and each is then 

 succeeded by a distinct interradial swelling. 



The interradial sutures can be distinguished in A, but are by no 

 means to be made out in B. 



The view of the patina from above (Remes, 1912, pi. iii, fig. 2h) 

 shows in A a patinal cavity, which Dr. Remes rightly describes as 

 spacious. He was unable to see the cavity in B, but I have convinced 

 myself that it was far more restricted. A proof of this is given by 

 the next observation. 



A cross-section of an interradial process, just above the level of 

 the radial facet, is given for A (Text-fig. 6) and B (Text-fig. 5). The 

 difference of form, though not great, is sufficiently obvious. The 

 difference of relative size is even more marked ; in A the ratio of 

 the interradial diameter of the process to the total diameter of the 

 patina is '33 ; in B the same ratio is "43. This means that the 

 diameter of the patinal cavity is less in B by 20 per cent. 



The radial facets are described by Dr. Remes as though they were 

 precisely similar in the two specimens. They have, no doubt, the 

 same general character, whicli,.as he justly points out, approaches 

 that of Eugeniacrinus rather than of Phylloerinus and Apsidocrinus ; 

 but the differences between them are fairly striking. In A (Text-fig. 7 ) 

 the radial groove proper is short and small, and little more than 

 a tongue-like depression at the bottom of the wide V formed by the 

 sloping upper borders of the muscle-plates ; in B (Text-fig. 3) it is 

 a deep U, of which the sides ascend almost vertically and meet the 

 corresponding upper borders of the muscle-plates at an angle which 

 approaches a right angle. The same difference finds expression in the 

 far greater height of the muscle-plates in B than in A, and this 

 height is due to an enlargement of the tract above the wide and deep 

 muscle-foss£e. This tract bears the articular depressions which 

 Dr. Jaekel (1891, p. 641, text-fig. 20) has named " Gelenkgruben ", 

 and has also shown clearly in his restorations of Eugeniacrinus 

 caryophyllatiis (1907, pp. 300, 301, text-figs. 21, 24). In A those 

 depressions are almost imperceptible ; in B they not only occupy 

 a larger field (as just explained), but seem, from the evidence of the 

 better preserved among the facets, to have been fairly pronounced. 

 The difference between the muscle-plates of the two specimens is 

 also apparent when the radial facets are viewed from above ; in 

 A (Text-fig. 8) the upper part of the muscle-plate projects right 



