JIOLLTTBCA. 43 



are not nodulous. The whorls in the latter arc not so rounded, 



decidedly more angular above, much more finely spirally ridged, 

 and bear upon the varices shorter, thicker, and more curved 

 spines, which are not purple-black tipped, but white, except 

 along the back, where there is a slight ridge of pale brown. 

 31. tribulus has a different apex, more convex whorls, different 

 coloration, and much coarser and nodose spiral ridging. The 

 number and position of the spines is seen to be very similar in 

 all three species when closely and carefully compared. 



13. Murex acanthostephes. (Plate V. tig. B.) 



Murex (Tribulus) acanthostephes, Watson, Journ. Linn. Soc, Zool. 

 vol. xvi. p. 596. 



Hal. Arafura Sea, N.W. Australia, in 32-30 fms. ; bottom — mud, 

 sand, and shells. 



The ' Challenger ' specimen was dredged very near the same spot, 

 in 28 fms. 



Shell in form and general aspect rather like 31. tenuisjaina, 

 Lamarck, but with a shorter spire, fewer spines, and a non-canali- 

 culate suture; whitish, stained irregularly with light olive-brown. 

 "Whorls convex, subangular and carinatcd above the middle, with 

 two or three fine spiral raised lines above the angle upon the 

 sloping and somewhat flattened upper portion, and two or three 

 similar lines below the angle. Varices three on a whorl, bearing 

 five spines upon the convex part and six on the very straight beak, 

 with three or four minute secondary ones reflexed and appressed to 

 the surface. The uppermost of all, arising from the carina at the 

 upper part of the whorls, is the longest, slightly curved, very erect, 

 and almost parallel with the axis of the shell. The next, Xo. 2, is 

 minute, No. 3 a little shorter than Xo. 1 and arcuate, Xo. 4 much 

 smaller, and Xo. 5 a little smaller than Xo. 3. 



The spines on the cauda are straighter than those above, hori- 

 zontal, or at right angles to the axis, the third, counting from 

 above, being a trifle the longest, the rest on each side becoming 

 successively shorter. The body-whorl is transversely lirate through- 

 out, the lira? varying in coarseness, the strongest corresponding to 

 the longest spines, and being only slightly wavy, whilst some of the 

 intermediary ones are almost subnodular. The three nuclear whorls 

 are light brown, glossy, and larger than those of 31. tenuispina. 

 The fourth whorl has about eleven short, open, and a little upturned 

 spines, forming a very pretty coronation at a subcentral angle, and 

 has no spiral lines above or below it, but a second series of hollow 

 spines below at the suture, smaller than those above. Length 

 37millim. : diameter 12, exclusive of spines. 



31. tenuispina, a near ally, has longer and more numerous spines, 

 a longer and more pointed spire terminating in a smaller apex, a 

 conspicuously channelled suture, and its sculpture is more pro- 

 nounced, the spiral ridges being more granular and the lines of 



