80 MBS. JANE LOxasTAFF ON [vol. Ixxiii, 



31. striatula, which consist of the later whorls of larger shells, give 

 the impression of having more slender spires (PI. YI, figs. 10 

 & 11). Other individuals are intermediate, such as the Brussels 

 tyjDe (PL YI, fig. 12) and some of the specimens from Strathavon, 

 Lanarkshire. 



The type example of 31. suhsiilcafa is remarkable for showing the 

 sinus in the outer lip, while the other specimens with one excep- 

 tion only indicate it by the lines of growth. The sinus does not 

 give rise to so distinct a band as in 3Ivrc]iisonic(, sensu stricfo, 

 and is sometimes difficult to discern, being formed of from two to 

 five threads similar to those ornamenting the rest of the surface. 

 The position of the sinus is most evident on shells with a slightly 

 worn surface. The majorit}' of the specimens have fine threads 

 intercalated between coai'ser ones, and two of the latter below the 

 band are generally stronger than the others on the whorls of the 

 spire. 



I consider that the shell described b}^ me as IlJiahdosj)h'a selkirkii 

 belongs to this species ; it occurred as an external mould in the 

 Main Lime at Braidwood, Carluke, and has unfortunately been 

 destroyed by fire in the Hunter- Selkii'k Collection, so that it is 

 now only represented by wax impressions. It is the anterior 

 portion of a large specimen ; the whorls are high., and show numerous 

 ornamenting threads. From the markings on the surface I was 

 led to think that the lines of growth were but slighth^ sinuated, 

 and that there was not a distinct sinus. As there is evidence of a 

 breakage near the aperture, and these markings are only observed 

 in that vicinity, they are probabl}' adventitious. The shape of the 

 shell and disposition of the ornamenting threads greatly resemble 

 some of the Belgian examples of A. ^triafula, especially the least 

 crushed one in the Ecole des Mines, Paris. 



The specimen designated as the variety" ((nn.'itroiif/iana (o^;. cif. 

 ]). 68 & pi. V, fig. 9) must be regarded as a distinct species, and 

 that represented by fig. 10 as merely a flattened and worn example 

 of the typical form. 



Holotype. — ^De Koninck did not select any one specimen as 

 holotype. The two early ty2)es in the Ecole des Mines, Paris, 

 agree very nearly Avith his specific description ; but the fragment 

 (PI. YI, fig. 11), consisting of two whorls alone, accords with the 

 enlarged draAvings, fig. 7 h of pi. xl, ' Anim. Foss. Terr. Carb, Belg.,' 

 and fig. 58 of pi. ix, ' Faun. Calc. Carb. Belg.' It has a length 

 of 10 millimetres, and its greatest width = 7 mm. 



The other shell (PI. VI, fig. 10), consisting of five whorls, does 

 not accord with either of the figures of a complete shell given in 

 these Avorks. The length = l(j millimetres, and the greatest width 

 of the penultimate Avhorl = 8"25 mm. 



The small Avorn specimen (PI. YI, fig, 12) in the Poyal Brussels 

 Museum, marked as the type in the later Avork, does not correspond 

 with any figure, although it belongs to the species. It consists 

 of eight whorls in a length of 9*5 millimetres, and has a width of 

 3"5 mm. 



