MOLLUSCA OF THE ^ CHALLENOEll ' EXPEDITION. 711 



B. 0-4', least O S. Penultimate whorl 01. Mouth, height 0*2, 

 breadth 0-17. 



This species somewhat resembles ia form T. tumidiis, Mont. ; 

 but, apart from difterences of texture, colour, and sculpture, it is 

 much less angulated and less broad on the base than that, and the 

 upper whorls are more tumid and more immersed. T.{M.) green- 

 landiais, Gh., it also resembles in form and size ; but, apart from 

 all differences of colour and sculpture, it is, than that, less 

 conical, more scalar, the suture is much more impressed, and the 

 whorls are more immersed. From T. (M.) U??m, W., it differs in 

 the whorls being much more tumid and the general form less 

 conical. From T. {M.) pompholiigotics, W., it differs in the last 

 whorl being far less tumid and out of proportion with" those 

 which precede. In contrast with T. (il/.) dnopherus, AV., the pad 

 on the pillar-lip is here rather on the outside, with the lip flat- 

 tened out upon it, while in that species the thickening is on the 

 inside, filling up the lip. 



15. Trochus (Mahgaeita) dnopheiius, W. {Ivotpepus, dusky.) 



St. 122. (Sept. 10, 1S73. Lat. 9^ 5' to 9= 10' S,, long. 34.° 49' to 

 34° 53' W. Off Pernambuco. 350 fms. Mud. 



Shell. — Depressedly conical, rather strong, semitransparent, of 

 a dark pearly iridescence. Sculjpture. There are spiral ridges, 

 strong, five above the base ; the first is close to the suture and is 

 exquisitely beaded from the middle of the second whorl ; the 

 beads are about thirty-five on the last, twenty -two on the penul- 

 timate whorl. The second ridge is remote from the first, and 

 forms a shoulder to the whorls. The third, fourth, and fifth oc- 

 cupy the periphery, which is carinated by the fourth till close up 

 to the mouth, when the fifth forms the carina. Four fine threads, 

 of which the first is partially beaded, lie in the flat between the 

 first and second ridge ; two between the second and third ; one 

 between the third and fourtli. Bolow ilic fiflii ridgo is a flat fur- 

 row narrower than the rest ; below the furrow is a sixth ridge, 

 slighter than the others ; and then the base is closely covered with 

 eleven spiral threads, which tend to become stronger and wider 

 apart near the umbilicus. The first three ridges alone appear on 

 the upper whorls. Longitudinally the whole surface is sharply 

 scored by the lines of growth. Colour a ruddy brownish white, 

 shot with a purple and green iridescence. Spire depressedly 



