ON CTENOSTREON BURCKHARDTI, n.sv., FROM THE MIDDLE 
OOLITES OF SWITZERLAND. 
By R. Burren Newton, F.G.S., etc. 
Read 9th May, 1902. 
PLATE V. 
Ratuer less than two years ago, the British Museum was indebted to 
Professor Rudolph Burckhardt, of the University of Bale, for some 
interesting material illustrative of a new species of Ctenostreon, 
which had been obtained by himself and his friend Dr. Ernst 
Sauerbeck from the IJacrocephalites macrocephalus zone at Tschapperli, 
near Bale in Switzerland. Eight examples of the Lamellibranch 
were sent, the two best preserved forming the subject of the present 
communication. Included in the same donation were two specimens 
of Ctenostreon pectiniformis (Schlotheim) [| = Lima _ proboscidea, 
J. Sowerby], which ranges through the Lower Oolite rocks into 
strata of Kimeridge age ; these were sent for purposes of comparison. 
The particular zone yielding this new Ctenostreon represents the basal 
member of the Callovian period, and consequently forms part of the 
Middle Oolite deposits ; the term Callovian being better known in 
England, perhaps, as the Kellaways Rock. 
Dr. August Tobler, one of the latest writers upon the geology of 
this area of Switzerland, furnishes the following list of molluscan 
species characterizing the Callovian beds at Tschapperli ! :— 
Macrocephalites macrocephalus (Schlotheim), 
Perisphinetes triplicatus (Quenstedt). 
Reineckia anceps (Reinecke). 
Cosmoceras Jason (Zieten). 
Pleuromya tenwstria, Agassiz. 
Rhynchonella triplicosa, Quenstedt. 
Ctenostreon proboscideum (J. Sowerby). 
Astarte, sp. 
Cucullea, sp. 
In remarking upon the genus it may be mentioned that Ctenostreon 
was established by Eichwald* in 1868 for the reception of two species : 
(a) Ctenostreon distans, Kichwald, from Russia, said to belong to the 
Neocomian, but in reality of Portland age (= Olcostephanus virgatus 
zone), and therefore Upper Oolitic; (b) Ctenostreon proboscideum 
(J. Sowerby), now regarded as synonymous with C. pectiniformis, 
1 “er Jura im Sudésten der Oberrheinischen Tiefebene’’: Verhandl. nat. Ges. Basel, 
vol. xi (1896), pt. 2, p. 306. 
2 Lethzea Rossica, vol. ii (1868), pp. 455-458, pl. xx, fig. 12. 
