F. R. Co/cpcr Reed — Salter's Undescribed Species. 357 



that the material is so badly preserved that even the genus is 

 doubtful. It is quite possible that it is a Horiostoma, but the 

 apparently alate margin reminds one of Pleurotomaria alata (His.)/ 

 and the shape of the whorls is also similar, especially in the variety 

 siibcarinata. 



Trochonema bijugosa, Salter. (PI. XV, Fig. 4.) 



1873. Trochonema bijuf/osa, Salter, n.sp. : Cat. Camb. Sil. Foss. Woodw. Mus., 



p. 156 («875). 

 1891. Trochonema bijugosa, Woods : Cat. Type Foss. "Woodw. Mus., p. 115. 



There are only two specimens of this species in the Woodwardian 

 Museum, and they are the original ones determined by Salter. The 

 larger one shows a portion of the body-whorl and succeeding whorl 

 with the shell well preserved ; the smaller one is merely an imperfect 

 internal cast of the two basal whorls, and it is doubtful if it is 

 rightly attributed to the same species. Both are from the Wenlock 

 Limestone of Dudley and belong to the Fletcher Collection. Salter 

 describes the species as "much resembling T. (Turbo) trochleatiis 

 of McCoy and Hall," and the figure in the margin appears to be 

 a rough restoration of it. 



Diagnosis. — Shell conical, turbinate ; of six (?) whorls ; apical 

 angle 60°. Whorls angulated by two parallel longitudinal keels, 

 between which their surface is flattened and vertical. Apical 

 surface of whorls sloping down steeply from suture-line to upper 

 keel, but swollen into a low, revolving ridge close below suture-line, 

 defined below by distinct groove. Lateral surface flattened vertical, 

 about one-third height of whorl, bounded above by upper keel and 

 below by lower keel ; lateral surface meets apical surface at 

 angle of 45°, and in basal whorl meets umbilical surface at same 

 angle. Umbilical surface sloping, faintly convex. Keels forming 

 rounded, projecting, parallel bands, marked off above and below by 

 faint narrow grooves. The lower keel is rather the larger of the 

 two. Surface of valves ornamented by regular, continuous, strong, 

 equal strife. On apical surface the stria? are oblique, and close to 

 the upper keel bend sharply back and cross it in a series of sharp 

 crescents resembling those on the slit -band of Pleiirotomaria. 

 Between the keels on the lateral surface the strife are nearly 

 straight and vertical, and cross the lower keel directly without 

 bending back, and continue thence on to the umbilical surface, 

 where they become sigmoidal. 



Measurements. 



mm. 



Width of larger specimen ... 20'0 



Estimated height of ditto 20-0 



Remarks. — It is unfortunate that the material on which this 

 species is based is not more complete, and accordingly the species 

 does not admit of very satisfactory definition. At any rate, it seems 

 to be distinct from any previously described. 



1 Lindstrom : Sil. Gastrop. Pterop. Gotl., p. 118, pi. x, figs. 33-37. 



