450 M. Vogt on some Inhabitants of the Freshwater Muscles. 



cimens derived from the Korallenkalk or white jura of Nattheim, 

 Wurtemberg, and to be seen in the collection of Fossil Tere- 

 bratulse of the British Museum, so beautifully worked out by the 

 indefatigable exertions of Messrs. Waterhouse and Woodward. 



Terebratula Deslong champ sii, nob. PL XV. fig. 6 a, b. 



Shell small, oval, subdepressed ; dorsal valve much more con- 

 vex than the ventral one ; beak straight, truncated by a large 

 foramen extending to the umbo of the ventral valve, partly sur- 

 rounded by the substance of the beak, by a small portion of a 

 disunited deltidium, and a part of the umbo. Valves closely 

 covered by numerous strong, short, tubular spines or granulations, 

 between which the punctuation is visible : this structure being the 

 same as that observable on all the lias Spirifers yet discovered, 

 gives to the shell a rough feel similar to that of Ter. lima (Def.), 

 but from which it differs completely. 



This remarkable little shell is placed provisionally among the 

 Terebratula, as I consider a knowledge of the internal appen- 

 dages essential before one can say positively to what genus an 

 unknown species belongs, as judging solely from external cha- 

 racters one may often be led to place a shell in a very inappro- 

 priate genus. It has the beak, deltidium and foramen of Wal- 

 tonia and Terebratulina, and, as can easily be seen, the internal 

 apophysary system in both differs completely, so that it may 

 perhaps belong to one of these genera. Length 3| lines, breadth 

 3 lines, depth 1J line. 



Only four or five specimens of this little shell are known as 

 yet in the collections ; viz. one specimen was found by M. Tesson, 

 two by M. Breville in the lias beds of Curcy, and one by myself 

 at Vieux Pont, between Caen and Bayeux. It was however fa- 

 miliar to M. Deslongchamps some years back, who kindly for- 

 warded me drawings he had made from M. Tesson's specimen. 

 I take much pleasure in dedicating this species to M. Deslong- 

 champs. 



PL XV. fig. 6. nat. size of the species ; 6 «, enlarged figures. 



XXXIX. — On some Inhabitants of the Freshwater Muscles. 

 By C. Vogt*. 



Since the interesting researches of M. Baerf, it is well known 

 that the freshwater Muscles are infested by a number of 

 Entozoa of extraordinary form : Cercarice, Bucephali, tailed Di- 

 stoma, and numerous other Trematoda in the state of larvse and 



* Translated from the Annales des Sciences Naturelles, Oct. 1849. 

 t Nov. Act. Acad. Leopold. Carol, vol. xiii. Pars 2. 



