100 Mr. H. E. Strickland on the genus Cardinia. 



(E. Lachenalii, but find the lowest leaves to be occasionally even 

 tripinnate, and the leaflets are quickly rounded off at the end to 

 an acute angle. I suspect that Mr. Ball is not acquainted with 

 the radical leaves of seedling plants or young offsets : they are 

 once or twice pinnate, with ovate or wedge-shaped, obtusely inciso- 

 apiculato-crenate segments. 



It only now remains for me to add, that I fully concur with my 

 friend in the observations with which he concludes his paper, 

 but think that the position, form, and relative size of the radical 

 knobs are of more value for the discrimination of species than 

 they appear to possess in his estimation. 



St. John's College, Cambridge, April 25, 1844. 



XIV. — On Cardinia, Agassiz, a Fossil Genus of Mollusca cha- 

 racteristic of the Lias. By H. E. Strickland, M.A., F.G.S. 



There are few groups of fossils which, both in their generic and 

 specific relations, have been involved in greater confusion than 

 the very natural and characteristic genus of which I am about to 

 speak. Having resided for some years in a locality where several 

 species of this genus abound, and having, by the examination of 

 many hundreds, I might say thousands of specimens, aided by 

 the kindness of Mr. J. Morris, author of the valuable c Catalogue 

 of British Fossils/ been enabled to trace them through their 

 several varieties, and thus to circumscribe the boundaries of the 

 species, I hope to correct some of the errors into which other 

 authors have fallen. 



The genus of Mollusks in question is evidently most nearly 

 allied to Astarte, Sow. (Crassina, Lamarck), a genus which most 

 authors agree in placing among the Venerida. From the great 

 strength of the shell, single valves are often preserved in a per- 

 fect state, and we are thus enabled to ascertain all its characters 

 with an accuracy that is rarely attainable in fossil bivalves, espe- 

 cially of the older formations. The genus may be described in 

 general terms as an Astarte with the addition of very strong 

 lateral teeth. The shell is longitudinally oval, very thick, equi- 

 valve, inequilateral, perfectly closed ; the hinge very strong ; the 

 right valve with two oblique converging cardinal teeth as in 

 Astarte, but these teeth are flat, and only divided by a slight 

 groove, which is sometimes obsolete. Below these teeth and im- 

 mediately behind the lunule is a depression extending in front of 

 the anterior lateral tooth, with a corresponding elevation in the left 

 valve, in which the true cardinal teeth are almost wholly obso- 

 lete. Above the cardinal teeth in both valves is a deep narrow 

 groove, evidently for the reception of an external ligament, as in 



