92 PROCEEDINGS OF THE 



affinity. The outline in the two plates appears to correspond, but 

 the proportional breadth is different, and the apophyses are widely 

 different in form. 



Locality and Horizon. — Gallowhill, near Strathavon, Lanarkshire ; 

 in shales of Lower Carboniferous Limestone group. 



Collection. — J. Thomson. 



Chiton, sp. ind.— (PI. II., fig. 10.) 



Obs. — The interesting specimen represented by Fig. 10 is again 

 from the cabinet of Mr. Armstrong. It is only a fragment of a 

 plate, probably an intermediate one, but introduces us to something 

 unusual in the way of apophyses or insertion processes. Instead 

 of the usual more or less triangular, lamellar plate, we observe the 

 lateral anterior margin of what must have been a large plate, pro- 

 longed into a simple spike-like apophysis. It is obliquely bent 

 downwards, and may be described generally as spike-like, or tooth- 

 like, projecting but little beyond the anterior margin of the plate. 



Locality and Horizon, — Law Quarry, near Dairy, as before. 



Collection, J. Armstrong. 



Chiton soleaformis* sp. nov. — (PI. L, figs. 18 and 19.) 



Sj). Char. — Acutely triangular, slipper-like, elongate, prolonged 

 backwards into a fine drawn-out point, sharply carinate in the 

 median line, arched. Front margin excavated, arched ; apophyses 

 very delicate, simply projecting forwards, not continued laterally 

 along the anterior margin. Surface microscopically granulated in 

 transverse lines ; no separation into areas by diagonal lines. On 

 the lower surface there is an elongately triangular, flattened in- 

 curved area, extending from the pointed posterior extremity, some- 

 what less than half the length of the plate, and with an unorna- 

 mentecl surface. Interior, shoe-like. 



Obs. — These elegant little plates have, at first sight, a resem- 

 blance to those bodies described by Mr. Kirkby as the mantle 

 spines of Chitonelhcs HancocJiianus.f These, Mr. Kirkby informs 

 me, are not hollow and open beneath, and cannot, therefore, have 

 any direct connection with the present fossils. Furthermore, in 

 certain of the recent Chitonidae, such as Chiton (Corephium) 

 acideatus, Lin., the spines implanted along the margins of the 



* From solea, ce, an open slipper, or sandal, 

 t Quart. Jour. Geol. Soc, 1859, xv., p. 622, t. 16, f. 5-8. 



