276 Reviews — 21. Cossmann — Eocene Mo/hisca. 



treatise, "Becherches Geologiqnes sur les terrains tertiaires cle la 

 "France occidentale " : Stratigraphie, first part. Bretagne (Annales 

 Sciences Geologiques, 1881, vol. xiii). Many of the shells in 

 Yasseur's work have hitherto had only a manuscript value, as 

 the intention of that author to fully describe and figure them in 

 a second part was never realized, if we except a few plates of fossils 

 which were subsequently issued without text. Although through 

 courtesy the name of Vasseur is still attached to these species, 

 now described for the first time, there is no doubt that M. Cossmann 

 must claim their real authorship. 



The present work, judging from this first part, promises to be 

 a large and important one, as all the species, whether new or other- 

 wise, are fully diagnosed and figured. A large number of the 

 shells, we are told in the preliminary remarks, can be undoubtedly 

 paralleled with Paris Basin forms ; a few being of Lower Eocene 

 age, whereas the majority belong to the upper portion of the Middle 

 Eocene. The groups now considered are : the Cephalopoda and the 

 Pulmonate and Opisthobranchiate Gasteropods. 



One of the most interesting facts brought out with reference to 

 the Cephalopoda is the discovery of a second specimen of James 

 de Carle Sowerby's Beloptera anomala; the only known example 

 prior to this was the type specimen from the London Clay at 

 Highgate, upon which Frederick Edwai'ds founded the genus 

 Belemnosis. The principal distinguishing character of the genus, 

 according to Edwards, was the large aperture " which forms a com- 

 munication between the alveolar chambers and the sac in which 

 the shell was lodged." If such an aperture were normal, it would 

 constitute a serious anomaly in the organization of the Cephalopoda ; 

 and Messrs. B. B. Newton and Geo. F. Harris suggested that it was 

 due to the imperfection of the Highgate specimen, which bears 

 traces of having been rolled. The last-mentioned authors showed 

 that the so-called ventral aperture was in reality only the initial 

 chamber of the shell brought to light by the removal of a thin 

 projecting part of the rostrum consequent on ill-usage. It is 

 interesting to note that the more perfect specimen discovered by 

 M. Cossmann, and described in the work under review, fully bears 

 out the theoretical conclusions of Messrs. Newton and Harris. The 

 latter, however, included the species in the genus Spirulirostra. 

 M. Cossmann thinks that the points of difference are of sufficient 

 importance to warrant the retention of Edwards' generic name : 

 " les Belemnosis," he remarks, " sont des Spirulirostra sans rostre, 

 et a phragmocone moins spiral." Without analyzing afresh the 

 interesting details brought forward by Messrs. Newton and Harris 

 respecting the generic position of this shell, we are inclined to 

 accept their theory ; the question of the length of the rostrum or 

 whether it is obtuse or pointed, not being, in our view, a prime 

 generic factor. Out of fifty-five shells reviewed, the following 

 are recorded as new species : — Cephalopoda : Belosepin Dufouri. 

 Gasteropoda (Pulmonata) : Limnaa Bourdoti, L. Govetensis, L. 

 adela ; Bulimus Dumasi ; Auricula namnetica, A. simplex, A. Heberti, 



