SPECIES OF MURCHISONIA. 



623 



and Goldfuss * have referred Devonian shells to this species. That 

 of the former differs from both of Phillips's figures; the more rapid 

 increase of the whorls, and the absence of the keels below the band, 

 distinguish it from the right-hand figure, while the whorls are more 

 excavated than those of the left-hand figure. The shell described 

 by Goldfuss, which I have examined in the Bonn Museum, in- 

 creases more rapidly, the band is formed of two keels placed close 

 together, and the whorls are more excavated. The Pleurotomaria 

 angulata of E. d'Eichwald f is evidently different, from its having 

 keels above as well as below the band, and it is also verv much 

 smaller. Of all the forms referred to this species, that described by 

 L. G. de Koninck % most resembles it. He considers his shell iden- 

 tical with the right-hand figure of Phillips ; but I have seen his type 

 in the Brussels Museum, and I do not think it is the same, as it 

 increases more rapidly, the sutures are more oblique, the sinal band 

 is formed of two keels, and the keels below the band are more 

 numerous. There is, however, a fragment of a shell on the same 

 tablet, which strongly resembles the tricarinate shell in the Gilbert- 

 son Collection, and may possibly be identical with it. 



It would be a great advantage to have, as the type of the species, 

 a well-defined shell such as that in the Gilbertson Collection, as its 

 marked characteristics readily distinguish it from any other of the 

 genus. I therefore append a fuller description. Shell elongated, 

 turriculated, composed of numerous angular whorls. Only fragments 

 are preserved, but a perfect specimen would probably consist of ten 

 or more whorls. The sutures are deep, and the whorls increase 

 gradually. Rather below the centre of each whorl there is a pro- 

 minent keel, on each side of which is a narrow groove, limited by a 

 fine line ; below this prominent keel there are two smaller keels, 

 one of which is about halfway between it and the suture, and the 

 other appears just above the suture. The prominent keel evidently 

 represents the sinus in the outer lip ; though the lines of growth are 

 not preserved on it, they are on the surface of the whorl, and curve 

 back to it above, and forwards below. Above the band, the surface 

 of the whorl is slightly concave ; below it is almost vertical, sloping 

 but little towards the suture. Mouth unknown. 



(PI. XXI Y. fig. 1.) A fragment consisting of two entire whorls, 

 and portions of two others from Bolland, is in the Gilbertson Collection 

 in the Natural History Museum. 



Length 33 millim., width of lower whorl 21 millim., height 11 

 millim. 



In the Burrows Collection in the Woodwardian Museum there 

 are four specimens of this shell from Settle, and there is also a large 

 cast from the same locality, which is probably this species. All the 

 specimens are more or less imperfect and imbedded in the matrix. 

 Part of the base of one specimen is preserved, and on it there are 

 three or four additional keels. The specimen figured (PL XXIV. 



* Petr. Germ. vol. iii. p. 25, pi. clxxii. fig. 5, a, b, c. 

 f Lethsea Rossica, vol. i. sect. ii. p. 1180. 



\ Faune du Calc. Carb. de la Belgique, vol. viii. pt. 4, p. 18, pi. xxxiv. fig. 4. 



