598 EEV. E. BOOG WATSON ON THE 



rounded, with a very contracted convex base produced into a 

 very long subconical snout, wbich is flexuous in front, wliere an 

 old snout-end stands off like a splinter. Suture a slightly im- 

 pressed line in tlie obtuse angle at the junction of the whorls. 

 Mouth oval, with a blunt angle above and another below, where 

 it is produced into the long, flexuous, and almost closed canal. 

 Outer lip very equally arched ; it rises on the body ; its edge 

 contracts, and is cut up into a series of blunt-tipped saw-teeth, 

 the deep and narrow cuts between which run back into the front 

 furrows of the spines ; the basal one of these saw-teeth is large, 

 flat, and very prominent. Inner Up spreads thinly and widely 

 but indefinitely on the body above ; on the base it separates from 

 the body as a thin, prominent, patulous lamina, curving round to 

 the right lower down, leaving behind it a deep chink, which con- 

 tinues as a furrow down the snout, where the labial lamina is bent 

 abruptly over, so as to cover and almost close the canal. H. 3'1 

 (to point of spines beyond apex 3'6). B. 0'93 (to tips of spines 

 2-2). Penultimate whorl, height 0-25. Mouth, height 2-65 (ex- 

 cluding canal 072), breadth 0'5. 



This singularly beautiful species resembles most of all M. 

 {T.) aduncospinosus, Beck ; but in that the direction of the 

 spines is different, standing out much more from the axis ; the 

 texture and ornamentation of the shell are quite different, the 

 earlier whorls not being ornamented with a double row of hollow 

 squamous spines as here ; the spire is in that much higher, the 

 whorls less angulated, and the apex is a minute prefect cone of 

 3| whorls. In M. (T.) ternispina, Lam., the earlier regular 

 whorls have somewhat similar hollow squamous spines ; but 

 there is but one row of these, and the apex is quite different. 

 M. tribulus, L., though at first sight very unlike, has some very 

 strong points of resemblance : it is a bigger, coarser shell, with 

 shorter, fewer, and more massive spines ; but the direction of 

 all these agrees pretty closely with those in the ' Challenger ' 

 specimen ; its spiral threads are enormous compared with those 

 of the other, and are rudely tubercled ; yet in neither species are 

 there any longitudinal ribs ; though the snout is very short and 

 thick compared with that of M. acantJiostephes, obliquely scored in 

 connexion with the spines where the other is smooth and much 

 more bent at the point, yet the bend has very much the same 

 character. In M. trihulus the whorls are constricted below, 

 which makes the suture dissimilar, yet the general form of the 



