Vol. 55.] ECTOMAEIA AND HORMOTOIIA. 269 



Remarks and Resemblances. — This species was first de- 

 scribed by Sowerby in ' The Silurian System' as Pleuroioma articidata. 

 Succeeding palaeontologists referred it to Murchisoyiia, but Salter 

 (' Cat. Cambr. & Silur. Foss.' p. 172) was the first to place it in 

 Hormotoma, which he regarded as a section of Murcliisonia. It is 

 remarkable for the height of the whorls and the great obliquity of the 

 lines of growth aboYe the band. In this latter character it resembles 

 H. Griffithi and H. antiqua. It is also like the former in having 

 high whorls and a submedian band, but the whorls are more convex, 

 and the shell is much smaller and more slender. The broad, very 

 slightly convex whorls and low position of the band distinguish 

 H. antiqua from it. 



Locality and Horizon. — The t5'pe-specimen(Pl.XXII, fig. 7), 

 which is in the Museum of the Geological Society of London, is from 

 the Upper Ludlow of Dog Hill, Ledbury ; it is compressed, and the 

 apex is broken, leaving five whorls, which measure 22 mm. in length 

 and 6| mm. in width. In the Woodwardian Museum examples of this 

 species are recorded from three different localities, namely, Lambrigg 

 Fell and Benson Knott, Kendal, and Dudley. The specimens from 

 the two first-named localities are too imperfect for identification. 

 That from Dudley is probably this species, but it is partly an internal 

 and partly an external mould, consisting of about nine whorls, which 

 measure 39 mm. in length (PI. XXII, fig. 8). The Museum of 

 Practical Geology, London, contains two specimens from the Lower 

 Ludlow of Ledbury, which are neither of them entire; one is 

 undoubtedly this species; the bad condition of the other prevents 

 certainty in its identification. There are also some casts from 

 Underbarrow, Kendal, marked M. articidata, which are not well 

 enough preserved to make out what they are. An examjDle in the 

 Piper Collection in the British Museum (Xat. Hist.), from the 

 Lower Ludlow at Colston's Corner, Ledbury Dome, is probably this 

 species, but it is so much weathered that it is impossible to be quite 

 sure. Mr. Madeley (Stourbridge) has a specimen in his collection 

 from the railway-tunnel shale of Sedgley. This shale is situated 

 above the Wenlock Limestone and below strata of Lower Ludlow 

 age. In the Science and Art Museum, Dublin, there is an internal 

 and also an external mould in rock of Wenlock age from Tonlegee, 

 Cong ; these are marked M. articidata, but their poor state of 

 preservation makes it impossible to determine the species. Ludlow 

 is given as another locality in ' The Silurian System,' but I have not 

 seen any well-authenticated specimens from there. Some casts 

 embedded in matrix in the Ludlow Museum, from the Upper 

 Ludlow of Whitcliff'e, are labelled articulata, but the surface is 

 absent, and the traces of the band which remain make it appear 

 narrower and more deeply grooved than in the type. Phillips^ gives 

 the following localities for this species : — Frith Farm, Malvern ; 

 Welsh Court, Bodenham, and Shucknall in the AVoolhope District ; 

 Llangibby in the Usk district ; Golden Grove in the Llandeilo 

 District ; and Marloes Bay. I have not, however, seen any 

 1 Mem. Geol. Surv. vol. ii, pt. i (1848) p. 258. 



