NATURAL HISTORY SOCIETY OF GLASGOW. 97 



Later writers have been in the habit of eliminating from the list 

 of palaeozoic Chitons, the Chiton (?) cordifer, de Koninck,* on the 

 authority of Baron de Ryckholt.f I would, however, join with 

 Mr. W. H. Bailly in pointing out % that, according to one of his 

 latest papers on this family, Prof, de Koninck by no means admits 

 this abolition, § but retains the species under the name of 

 Chitondlus. There is no doubt that the so-called C. cordifer, 

 de Koninck, whatever its nature, and Chitondlus subquadratus, 

 K. and Y., do approach one another closely, and the plate above 

 described appears to combine some of the characters of both. 



The re-occurrence of a plate of this old form of Chitonellus in 

 the Law Quarry bed is not one of the least interesting facts to be 

 gleaned from Mr. Bennie's gatherings at that locality. 



Chitonettus, sp. ind. (?).— (PI. II., figs. 6 and 7.) 



Sp. Char. — In marginal outline almost square, but a little 

 longer from before backwards than broad ; pyramidal and slightly 

 arched, acuminating upwards ; lateral margin parallel, straight, 

 or a little bi-convex ; anterior margin slightly rounded ; posterior 

 margin concave, the angles pointed and a little produced. The 

 exposed portion is represented by a patelloid cap, rather more 

 anterior than posterior in position, and with a well-defined raised 

 margin separating it from the inverted portion of the plate ; apex 

 curved backwards, and rather depressed, but not overhanging the 

 posterior margin ; within the margin two or three rows of promi- 

 nent granules, succeeded by those of a second order, which gradu- 

 ally die out before reaching the apex. The surface of the inverted 

 portion of the plate around the exposed parts is marked by many 

 radiating non-granular ridges, which are much stronger and better 

 marked towards the anterior. 



Obs. — It is quite within the bounds of possibility that this may 

 be only another plate in the economy of the last described species. 

 The general character of the plate is the same, although the much 

 squarer form hardly points in this direction. The granulation is 

 likewise much more marked, and the radiating striae on the 

 inserted surface stronger. 



* Descript. Animaux Foss., p. 324, t. 22, f. 5. 



t Bull, de V Acad. E. de Bruxellcs, 1845, xii., pi. ii. p. 60. 



+ Jour. Geoi. Soc, Dublin, 1860, viii. , p. 170. 



§ Annals and Mag. Nat. Hist., 1860, vi., p. 95. 



VOL. V. G 



