Bibliographical Notices. 293 



that Linnaeus included both Planorbis carincttus and marginatus 

 under the name Helix planorbis, and that Helix complanatus is 

 synonymous with Planorbis nitidus, Midler. " ' Deorsum carinata,' " 

 he observes, " is equally applicable to nitidus " as to marginatus ; 

 "whilst 'supra convexa — subdiaphana — apertura semicordata ' 

 (Fauna Suecica) is much more critically correct when affirmed of 

 that little shell than of its larger rival ; and as ' parva admodum ' is 

 applied to it in the ' Fauna Suecica,' in the contrast of its features 

 with those of the preceding species, I feel no hesitation in asserting 

 the identity of nitidus with the Linnaean Helix." Surely Midler was 

 right, when he said of such names (impossible to be identified with the 

 species they were intended to represent), " oblivioni dandos reor." 



The chief confusion, however, which Mr. Reeve introduces into 

 the genus Planorbis is by his adoption of the views of Moquin- 

 Tanclon respecting the Planorbis nitidus of Midler. That name is 

 here applied to Planorbis (Segmentina) lineata (Walker) ; while the 

 shell which has hitherto been known to British conchologists as Pla- 

 norbis nitidus is called P. fontanus (Lightfoot). Now, on what 

 grounds is this change made? Midler's description of the species in 

 his * Historia Vermium ' is very full, and agrees most accurately with 

 P . fontanus until we reach, at the end, this sentence, " Ultra quin- 

 quaginta examini subjeci, quorum quidam strigis duabus ligamen- 

 torum instar in superna parte extimae spirae, forte ex restauratione 

 fractae testae, notantur." Now what does this sentence prove, but 

 that the majority of the shells he examined were Planorbis fontanus 1 

 to which species therefore his name should be applied. It is quite 

 possible, though far from certain, that the author confused the two 

 species, and that " quidam strigis duabus ligamentorum instar " has 

 reference to specimens of P. lineatus ; but such specimens were de- 

 scribed as the variety, while P. fontanus is clearly the type of the 

 species. And this becomes more evident when we find all allusion 

 to the variety omitted in the subsequently published ' Zoologiae 

 Danicae Prodromus,' the description in which work applies only to 

 the type. 



Mr. Reeve describes 128 species. His estimate of our land and 

 freshwater Mollusca differs from that of Forbes and Hanley in the 

 omission of Helix aperta, and the addition of Testacella Maugei, 

 Vertigo Moidinsiana, Conovidus Myosotis, Cyclas pisidio'ides and 

 C. ovalis. And as compared with the species described in Jeffreys' s 

 work, we find Anodonta analina and Pisidium roseum omitted, and 

 Testacella Maugei, Pisidium obtusale, Casertanum (cinereum) and 

 Henslowianum, and Cyclas pisididides added. Moreover Jeffreys 

 considers that Hydrobia ventrosa has a claim to be inserted as a 

 freshwater shell. But Reeve denies the species a place ; while, on 

 the other hand, he admits the Conovuli and Assiminia Grayana, 

 which are rejected by the former author. 



Mr. Reeve gives a map, in which, by a deeper or lighter tint of 

 colour, it is intended to show the boundary of the Caucasian province 

 of Mollusca, over which the British species range, and to indicate 

 the part in which the most characteristic of the genera and species 



