526 MR F. R. COWPER REED ON 



shaped plates have been found. The material is too imperfect for specific description, 

 but the form seems allied to T. scotica. 



From the above description of fairly perfect specimens of Turrilepas Peachi from 

 Girvan it seems legitimate to doubt if this and its allied species are congeneric with 

 T. Wrightii, if we strictly adhere to Dr Woodward's original description of the type. 

 Clarke has remarked on the want of definiteness in our knowledge of the latter, but the 

 specimen of T. Wrightii seems to be referable to the peduncular part of the barnacle. 

 The question arises whether we are to regard the fossils mainly built up of the kite- 

 shaped plates as the capitular portion of the same genus. The structure as now revealed 

 does not seem to commend this theory, and though one may be unwilling to go back to 

 the old idea of the fossil belonging to the polyplacophorous molluscs, yet it is difficult 

 to maintain its reference to Turrilepas in its strict sense. On the other hand, it seems 

 to bear a considerable resemblance to the genus Strobilepis of Clarke # from the Hamilton 

 Group of New York, which is described as having four vertical rows of plates, i.e. two 

 lateral rows of large plates symmetrically disposed and an intermediate ventral and 

 dorsal single series ; the ventral series consists of spines. Our forms differ by having a 

 double instead of a single dorsal series, and the ventral surface is unknown ; but other- 

 wise there are some striking points of similarity in the regular arrangement of the plates 

 and the symmetrical shape of the fossil as seen in a dorsal view, and Clarke is not 

 quite satisfied as to the true position of the ventral row of spines. 



With regard to foreign species referable to the same genus as T. Peachi and 

 T, scotica, it may be mentioned that the plate described under the name of T. cana- 

 densis, WooDWARD,t from the Utica States of Canada, bears a close resemblance to the 

 form from the 07'this argentea beds of Haverfordwest. T. Mitchelli, Etheridge jun.,| 

 from the Wenlock beds of New South Wales, is known by kite-shaped, " cancellated," and 

 median plates, according to the published figures, but Etheridge thinks the median 

 plate represents another species. The several allied Bohemian species, described by 

 Barrande as Plumulites, are referred to by Etheridge and Nicholson in their accounts 

 of the Girvan species, and there is no need to discuss them again here. 



The latest known species, stratigraphically, which have been described are those 

 from the Hamilton Group of New York.§ Most of them are founded on isolated plates 

 which possess either the shape of the median plates of T. Peachi and T. scotica or the 

 so-called " cancellated plates " of the latter ; no typical kite-shaped plates have been 

 described. The conical, strongly folded plate of T. (?) Newberryi (Clarke, op. cit., 

 p. 219, pi. xxxvi., fig. 16) much resembles the figured one referred by Etheridge and 

 Nicholson to T. scotica (Etheridge and Nicholson, op. cit., pi. xiv., fig. 25) which has 

 been discussed above ; and Clarke remarks how widely this differs from the plates 



* Clarke, Palseont. New York, vol. vii., 1888, p. 212, pi. xxxvi., figs. 20-22 ; Amer. Geologist, xvii., 189G, p. 138, 

 pi. vii., figs. 11, 12. 



+ Woodward, Geol. Mag., Dec. hi., vol. vi., 1889, p. 274, woodcut. 



1 Etheridge jun., Geol. Mag., Dec. iii., vol. vii., 1890, p. 337, pi. xi., figs. 1-5. 



§ Clarke, Pahvant. New York, vol. vii., 1888, pp. 215-220, pi. xxxvi., figs. 1-19, 



