some Silurian Leperdltife. 171 



agrees entirely with me as to the Leperditke. Your figs. 15 

 and 16 I regard as L, inliaseolus^ because the two spots are 

 visible. The locality of Randefer in Oesel belongs to the 

 uppermost (Ludlow) strata of that island ; and L. pJiaseolus 

 and L. grandis arc the only Leperditue there in that stage. 

 It was my opinion also that L. 2>haseoIus, His., is the same 

 as my L. Angelini ; but I changed the name, as Hisinger 

 had apparently mixed different forms in mentioning Z.^^/^a6-eo- 

 las as got from Wisby, where L. liisinrjeri only is met with. 

 Kolmodin, in citing L. phaseolus from Wisby, merely follows 

 Hisinger. Its geological position is in the uppermost 

 (Ludlow) strata of Southern and South-eastern Gothland. 



"4. I have lately got some new materials of the original 

 ' Cypridina marginata^ Keyserling *, from the Petchora 

 country. The characteristic margin is visible only on casts, 

 and not on well-preserved specimens. The right valve shows 

 an angular prominence on the ventral border, like your Leper- 

 ditia arctica^ but nearer to the posterior end. I will describe 

 the species fully in a supplement to my memoir on the 

 Russian Leperditke^ together with some other forms of that 

 genus." 



I. I have to remark that, in accordance with M. Fr. 

 Schmidt's suggestions, L. hcdthica and L. Hisingeri are more 

 distinct specifically than I was inclined to consider them. Their 

 collocation with certain Silurian horizons is of great interest ; 

 but we must be careful not to limit " species " too strictly to 

 definite strata, in case the distinctions become too artificial. 



II. I was wrong to give latitude to Isochilina in the deve- 

 lopment of the ventral margin rather than to Leperditut in 

 diminution of that feature. But as the specimen from Rupert's 

 Land is distinct, in M. Schmidt's opinion, from Schrcnck's 

 and Romer's species, and is still an Isochilina^ we can retain 

 the specific name given to it at page 347, but as /. grandis, 

 Jones, instead of "/. grandis (Schrenck)," Schrenck's species 

 being a Leperditia with a slight inversion of the ventral 

 margin. 



III. If we follow M. Schmidt's well-founded suggestions, 

 we shall regard my fig. 5 (j)l. xix.) as L. Keyserlingi, 

 Schmidt ; fig. 6 as L. gracilenta, Jones ; fig. 14 as L. tyraica, 

 Schmidt ; fig. 16 as L. jiliaseolus ; and his own " fig. 22 " 

 as L. halihica, var. contracta, Jones. The other forms in 

 pi. xix. of my " Notes," viz. figs. 3, 4, 7-13, 15, and 17, 

 remain as there named. 



Your obedient Servant, 



T. Rupert Jones. 



* See Ann. & Mag-. Xat. Hist. November 1881, p. 347. At line 4 of 

 the page, /or Upper-tSilmiau reac/ Lower-SUuriau. 



