436 Mr. T. Davidson on Lamarck^s species of 



Geol. Soc, Nov. 1846, it was attributed to Terehratula ovalis, 

 Lamk., by mistake. Lamarck's var. b. does not belong to the 

 same species or epoch ; it is a young specimen of some oolitic 

 species, and is stated to come from Saturnin near Domfront, dep. 

 de la Sarthe. 



Both the species and variety may be seen in B. Delessert's col- 

 lection, and I may here state that every time I mention B. De- 

 lessert's collection, I mean that part belonging to Lamarck's 

 series. 



16. Terehratula ovalis, Val. in Lamk. PI. XIII. fig. 16. 

 T. testa ovali, transversim et supeme dilatata, striis concentricis Isevi- 



bus : nate incurva. 



Obs. This species is quite distinct from Terehratula dei^ressa, 

 and is from the white jura or coral rag of Wurtemberg. Mr. 

 Waterhouse showed me several young specimens referable to this 

 species in the collection of the British Museum. In B. Deles- 

 sert's collection. 



17. Terehratula numismalis, Val. in Lamk. PL XIII. fig. 17. 



T. testa subrotunda, Isevi, utraque valva supeme sinu instructa : striis 

 concentricis remotis : nate brevi : foramina minimo. 

 Ohs. This species is well known, has often been described and 

 figured, and requires therefore no further remarks, except that I 

 could not find the type specimen in the Paris collections ; but as 

 reference is made to tab. 240. fig. 1 «, b, of the ' Encyclopedic 

 Methodique' by Lamarck, no doubts can exist. I have therefore 

 figured here a magnificent specimen of the species from the liasic 

 beds of Normandy belonging to M. Deslongchamps. Ter. Cor, 

 No. 22, is merely a bilobate variety of this species. 



18. Terehratula umhonella, Val. in Lamk. PI. XIII. fig. 18. 



T. testa elongata turgida, transversim compressa, supra obtusa, Isevi : 

 umbonibus pre-elevatis : nate incurva. 



Ohs. This species has a strong resemblance to Terehratula 

 lagenalis, Schloth., 1820; one specimen shows the deltidial area, 

 while in others the umbo of the ventral valve touches the beak ; 

 this is visible in our English specimens of lagenalis ; it was 

 figured in the 'Encyclopedic Methodique,' pi. 240. fig. 3, but 

 the characters of the species are not well represented. Six s])e- 

 cimens are to be seen in B. Delessert's collection ; and on a 

 ticket written by M. Menard we find, " de Montigny, commune 

 de Mont-Bizol sur la Sarthe, k trois lieues de Mans.'' 



19. Terehratula diyona {Sow. M. C. tab. 96. fig. 1. 5). 

 Obs, Several specimens are to be seen in B. Delessert's col- 

 lection. 



