20 FOSSIL ESTIIERLE. 



The little River Pehrse, which there empties itself into theDima, runs in a deep gorge, in 

 which many beds of impure concretionary limestone are seen to alternate with courses of 

 calcareous shale or marl. These alternating strata, occupying a thickness of about 100 

 feet, repose on a band of arenaceous limestone, distinguished by impressions of fucoid-like 

 or polypiform bodies, and beneath it is a bed of concretionary limestone with marly lime- 

 stone, in which are remains of Ctenacanthus serrulalus (Ag.) and Osteolejns, &c, both of 

 which genera occur in the Old Red Sandstone of Scotland." 



The marls of Kokenhusen are referred to by Col. G. von Helmersen, in a work on the 

 geology of the central parts of Russia. 1 



At p. 71, he says : — " The Devonian formation towards the east (as far as is known to 

 me) consists of the same dolomites, calcareous beds, and marls, as occur near Kokenhusen, 

 of which on the Schelon only the lower member is conspicuous, and particularly the marls 

 are much developed." The marl, he says at pp. 72 and 73, is ' c one of the lowest beds 

 of all the Devonian calcareous strata ; it is characterised at places by Spirifer Anossoffi, 

 Sp. Archiaci, Orthis crenistria, Mtirchisonice, Euomphalus Voroneiensis, corals, and some 

 few fish-remains. On the Dwina, a similar bed appears to correspond with this blue 

 marl ; it contains, besides very numerous fish-remains, only Lingula bicarinata and 

 Posidonia {rugosa, Kut.). It rests immediately on the sandstone of the Devonian forma- 

 tion, which, so largely developed in Livland, is altogether wanting on the Don and 

 Woronesh." At pages 41, 44, &c, Von Helmersen also gives sections seen at Mzensk, 

 Jefremow, &c, where the marls are intercalated with limestone, and rest on a limestone 

 that has Spirifer Anossoffi, Serpnla, Nucula, corals, and some fish-remains. 



On the River Torgel, in Livland, Dr. Pander found that the hard white sandstone, used 

 for grindstones, contains fine remains of Asterolepis (Pander), and that the overlying 

 bluish marls and clays contains scales and teeth of Osteolejns, Dipterus, and Glyptolepis, in 

 company with the Asmusia membranacea of Pacht. ' Ueber d. Saurodipt,' &c, 1860, p. iv. 



Through the kind intervention of Col. G. von Helmersen, I have been favoured with 

 the following bibliographic history of Asmusia membranacea, drawn up by Dr. Ch. 

 Pander, the eminent palichthyologist, who has taken much interest in this species, has 

 himself recognised its crustacean character, and has courteously favoured me with some 

 specimens from Kokenhusen : 



1 • Geognostische Untersuchungen in der mittleren Gouvernements Russlands, zwischen der Diina und 

 Wolga, in der Jahren, 1850 und 1853, ausgefiihrt von G. v. Helmersen und R. Pacht.' [Including R. 

 Pacht's 'Geognostische Untersuchungen zwischen Orel, Woronasch, und Simbirsk im Jahre, 1853.'] 

 Herausgegeben von G. v. Helmersen. Gedruckt auf Verfiigung der Kaiserlichen Akademie der Wissen- 

 schaften. ('Beitrage zur Kenntniss des Russischen Reiches und der angranzenden Lander Asiens,' 21. 

 Banchen.) 8vo, St. Petersburg, 1858. 



In this work are included some of the results of the labours of that promising young geologist and 

 traveller, Raimund Pacht, above named, who, we regret to learn, from Col. von Helmersen's Introduction 

 to the 'Geogn. Untersuch.' died in 1854, at the early age of thirty-one. 



