320 Mr. Sowerby on two 92ew Species ofOrhipula. 



verse and deep grooves, which are close set, being about half 

 their length distant from each other. I cannot ascertain whether 

 there is any natural opening in the center or not. The whole is 

 changed into crystalline Carbonate of Lime coloured by iron 

 rust ; and it lies upon a mass of Limestone containing remains of 

 Encrini and Madreporiies; a single spiral univalve is also to be 

 observed. From the falls of the Chaudihrey on the Ottawa River 

 in Lower Canada. 



Reference to the Plate. 

 Pl. XL 



Fig. 1. Caryocrinites ornatus, h, the pelvic plates; c. the costal 

 plates. 



2. Pentremites florealis. a. natural size ; b. pelvic or costal 



plates ; c. the scapular plates ; d. the interscapular plates ; 

 e. the ambulacrze ; /. the five terminal apertures surround- 

 ing the mouth ; g. pelvis. 



3. Pentremites Derbiensis. a. natural size; b. pelvic or costal 



plates ; c. the scapular plates ; d. the interscapular plates ; 

 e. the arahulacrse ; /. the five terminal apertures surround- 

 ing the mouth. 



4. Pentremites elliptica. a. natural size; b. pelvic or costal 



plates; c. the scapular plates; d. the interscapular plates; 

 e. the ambulacrae ; /. the five terminal apertures surround- 

 ing the mouth. 

 6. Fossil animal belonging to the family of Asteriad<E from 

 Canada. 



Art. XXXVIII. Descriptions of two new species of the 

 Genus Orbiculs, By G. B. Sowerby, F.L>S, S^c, 



Dr. Bigsby's researches in Canada have, among other novel- 

 ties, produced one of tlie two new species of this singular genus 

 here described, and the other has been found without any locality 

 among the stores so long preserved by Mr, G, Humphrey, I have 



