186 DE. C. T. TRECHMANN ON [vol. Ixxiii, 



Pleltiiotomaeia (Sisenna) hectoei, sp. nov. (PL XYIII, 

 figs. 5 a-5 c.) 



Shell consisting of about seven whorls ; the spire is depressed ; 

 i^he upper surface of the first three whorls is nearly flat, but in the 

 later whorls it is rather concave and slopes towards the line of nodes. 

 'The slit-band occurs about two-thirds of the distance above the base 

 of the bodj^- whorl and nearly half the distance above the suture of 

 the penultimate whorl. The earliest whorls seem to be smooth, 

 A row of heavy rounded nodes occurs both above and below the 

 slit-band ; those below it project beyond the slit-band, and form the 

 keel of the shell. The nodes above and below the slit-band are of 

 .about equal size, are rather irregula rly spaced, and occasionally tend 

 to coalesce one with the other. The slit-band has a faint furrow 

 Above and below it, and between it and the nodes. Below the keel 

 the surface of the shell is slightly concave ; it then becomes convex, 

 and then again concave towards the umbilicus, which is partly 

 covered and obscured by a thin callosity of the inner lip. Below 

 the keel the growth-lines bend sharply backwards, and then curve 

 forwards again and pass to the umbilicus. This forward curving 

 produces a tongue-like j^rojection of the lip below the notch. The 

 notch of the lip is about 10 mm. deep, the diameter of the shell is 

 34 mm., its height 20 mm., and the height of the spire 15 mm. 



Locality and horizon. — Bed c, Otamita (Hokonui Hills). 

 Carnic. I collected two or three very fine specimens here. I also 

 found casts of it in the Carnic beds in the river-section of the 

 Wairoa Gorge, and a cast of this (or of a ver}^ similar shell) in 

 the Noric beds, with JPseudomonotis ocliofica, at Grarden Gulh', in 

 the Nelson district. 



Remarks. — This shell may be placed in Koken's Pleurotomarid 

 group Siseiina, which includes several Upper Triassic forms having 

 a depressed spire, step-like whorls, and the slit-band situated be- 

 tween two ridges on the upper and outer side of the whorl. The 

 tongue-like projection of the lip below the notch is also charac- 

 teristic of this group. Koken says, however, that in Slsenna the 

 umbilicus is open, whereas in the form here described it is partly or 

 completely covered. It bears a rather remote resemblance to a shell 

 from the Upper Trias of Bear Island in the Arctic Ocean, called 

 by J. Boehm Sisenna conwentzi} in which the umbilicus is also, as 

 in the present shell, covered by a thin labial callosity. 



Pleueotomaeia hokoxtjieis'Sis, sp. nov. (PI. XVI] I, figs. 

 6«-6 c.) 



Shell small, consisting of seven whorls increasing rather rapidty. 

 The apex is pointed, and the earliest whorls are angular. About the 

 fourth whorl a row of verticall}^- elongate nodes appears below the 

 suture, together with five or six spiral thread-like lines, one of 

 "which crosses the centre of the line of nodes. The ornamentation 



1 Bibliography, 8, p. 51 & pi. vi, figs. 1, 9, 10, 16 



