562 Scientific Proceedings, Royal Dublin Society. 



forking occasionally. Concentric ornament distinct, making the ribs look as 

 though set with imbricated scales directed backwards. Pedicle valve very 

 convex. 



A form resembling, if not identical with, this occurs in the lower part of 

 Worsaw Knoll, near Pendle Hill (probably Cj). 



Sinrifev, sp. (P). XXXVJ, fig. 6.) 



HOLMPATRICK LiMESTONE. 



Pedicle valve: — Ribs on flanks tall, angular, forked, or oeoasionally split 

 into three. Forking usually occurs near the umbo, but may be delayed 

 until close to the anterior margin. Sinus deep, angular. Ribs in sinus 

 indistinct ; quite absent towards the anterior end in some specimens. Con- 

 centric liueation very marked towards the anterior margin. Area broadly 

 triangular, extending to the greatest width of the shell. 



Brachial valve not known with certainty. 



Spirifer cf. convoluius, Phil. (PI. XXXVil, fig. 6.) 

 Rush Slates, R 6 b. 



An imperfect pedicle valve. Width at least 70 mm.; length about 30 mm. 

 Resembles Sp. convolutus in the nature of its ribbing. The ribs near the 

 sinus are wide, often splitting into two or three ; those nearer the cardinal 

 angles are much narrower. Two sharp, prominent ribs bound the sinus, which 

 is V-shaped in section. The anterior part of the sinus is missing. Poste- 

 riorly it has smooth sides, the bottom being occupied by a. single, narrow 

 rib. 



