3i6 Records of the Indian Museum, [Vol. XIII, 



Fairly large, of a variable but moderate decree of elongation, 

 with rather broad slightly conoidal spire measuring about five- 

 ninths of the total height, with broad body-whorl somewhat ab- 

 ruptly contracted anteriorly into a rather f;hort stem correspond- 

 ing to the terminal canal. 



The protoconch, when fully preserved, constitutes a remark- 

 ably beautiful object. It is slightly oblique to the axis of the re- 

 mainder of the shell. It is shaped like a Turbo, broadly conoidal 

 in outline. It consists of a minute, highly glazed, slightly excen- 

 trie nucleus followed by four spire-whorls of which the two first are 

 very low and very broadly conical, the two last much taller and 

 rather strongly convex. The first whorl is smooth. The three 

 others are covered with very delicate sharply angular ribs stretch- 

 ing from suture to suture, slightly curved, with forward directed 

 concavity, and most of them very oblique and anteriorly antecur- 

 rent except on the last half of the last whorl when they become 

 practically vertical. In some specimens the transition to the spire 

 proper is quite abrupt, while in other cases a gradual shortening 

 of the protoconch ribs establishes a transition into the crenulations 

 of the sinus band. The protoconch is followed by seven and a 

 half spire- whorls, the height of which is generally equal to two- 

 fifths of their width or slightly more in the case of specimens with 

 a relatively narrow spire ; the maximum thickness being situated 

 nearer to the anterior than to the posterior margin of the whorls, 

 and coinciding with the zone of accretions to the apertural sinus. 



The sutures are rather deeply incised and are surrounded by 

 a prominent broad ridge or swelling, while another ridge of the 

 same character, corresponding with the zone of accretions to the 

 apertural notch, occupies a more anterior position upon the whorls. 

 The anterior margin of the whorls forms a deeply sunken zone 

 between the sinus ridge of one whorl and the circumsutural ridge 

 of the next whorl, proportionately scarcely broader than that be- 

 tween the two ridges of one whorl; and, in many specimens, as 

 both ridges are equally prominent, the spire usually assumes the 

 appearance of a cone very evenly encircled at close intervals, the 

 grooves being of about the same average width as the ridges. In 

 a few specimens, the circumsutural ridge is decidedly less promi- 

 nent than the sinus band, and the spire thereby acquires some- 

 what more of a stepped appearance. Both ridges are bifid, the 

 two component spiral threads being both equal in the case of the 

 sinus ridge, while, in the case of the circumsutural swelling, the 

 more anterior thread, to a degree varying in different specimens, 

 is more prominent than the posterior thread which either imme- 

 diately adjoins the suture, or is separated from it by one or two 

 fine raised spiral lines. Three raised spiral lines or minor threads, 

 of which the more posterior one is usually much thinner than the 

 two others, are observed along the floor of the groove separating 

 the two main ridges of each whorl Two more spiral threads may 

 occur along the depressed zone anteriorly to the sinus ridge, or 

 else, there may be but one, as the more anterior of the two may 



