Mr. F. A. Bather on British Fossil Crinoids. 3o3 



EXPLANATION OF PLATE XIV. 



(Illustrating the structure of the Dorsal Cup in the genera of 

 Fistulate Crinoids.) 



With the exception of the bottom line the figures follow each other in 

 four vertical rows ; three fourths of the bottom line is occupied by the 

 Calceocrinidae and Catillocrinidse. Each row again is divided into five 

 vertical columns : the first column on the left contains the simple generic 

 diagrams ; the circlets of radials, basals, &c. are indicated by letters placed 

 on the left, and in some cases where any doubt might arise letters are 

 inserted in other positions, but this is only done where all writers are 

 agreed as to the homologies and the anal plates are never lettered : the 

 next four columns contain diagrams of the anal plates and the posterior 

 radial ; these are lettered in accordance with the different views as to 

 their significance. The second column contains the views of Wachsmuth 

 and Springer in 1879 (figs. 3, 5, 6, 7, 8, 15, 16, 17, 25), the third column 

 those of P. II. Carpenter in 1882 (figs. 1, 2, 3, 4, 5, 15). _ The views which 

 these authors then held as to other genera were not definitely expressed by 

 them, but they may easily be inferred from those that are given. The 

 fourth column gives the latest views of Wachsmuth and Springer (1886), 

 which it is presumed they still hold (all figs, except 9, 10, 12, 14, 19, 28, 

 29, 31). In the fifth column are indicated the views that seem to me 

 more probable. 



In each generic diagram the Left Anterior Interradius is on the ex- 

 treme left and the Anterior Radius is on the extreme right : thus the 

 position of the Posterior or Anal Interradius is always the same. 



Explanation of the Lettering. 



IB. Infra-basal. 



B. Basal. 

 R. Radial. 



C. Costal or Brachial. 



Rx. Lower half of a bisected 



Radial. 

 R'. A Rx that has assumed anal 



functions, P. II. C. ; Radianal, 



F. A. B. 

 Az. Azygos, W. & S. 

 X . Special anal plate, W. & S. ; 



Brachianal, F. A. B. 

 t, First plate of tube, W. & S. ; 



Second Brachianal, F. A. B. 



Notes on the Figures. 



1. Hoplocrinus dipentas. The type specimen differs in its anal area from 

 the variety shown in fig. 2. The specific name is given here, as 

 in all cases where the generic diagram has been taken from one 

 species more than another. 



3. Hybocrinus. Hybocystis is of essentially similar structure in the anal 



area. 



4. Baerocrinus. The cracked lower right-hand corner of the 11. post. 



Radial has been with insufficient reason regarded as an anal 

 opening. 



6. Heteroerinus. This= Stenocrinua of W. & S., a genus founded on the 



type species of Heteroerinus, II. heterodactylus. Qhiocrinus ia 

 of essentially similar structure in the anal area. 



7. Ectenocrinus of S. A. M.il\er=Heterocrinus of W. & S. Type is 



Heteroerinus simplex, Hall. Herpetocrinns appears to be closely 

 allied to this, but structure is uncertain. 



{W. & S. have as yet had no opportunity 

 of expressing their opinion on these 

 forms, which are alone enough to 

 upset their published views. 



