Miscellaneous. 283 



sing nuclei of cells or bundles of crystals. The formation of the 

 indigo is in connexion with the non-development of the fecula, so 

 that the more there is of this substance the less there is of the blue 

 product. Whence it follows that the young leaves being less feculi- 

 ferous than the old ones, are more useful. 



"The chlorophylle is a formation prior to the fecula, which is 

 developed in separate nuclei in the green granules ; but there is 

 nothing to prove that the indigo is influenced by the chlorophylle, 

 or that it is the anthocyan, the blue principle of the chlorophylle, 

 which has any connexion with the indigo, so that the leaves of a 

 bright and uniform green are also those which are best adapted for 

 the extraction of indigo ; for the greener and more healthy a leaf is, 

 the more it contains of the blue principle." — Extract from the Bul- 

 letin de VAcad&nie de Bruxelles, 1838. 



ON A NEW SPECIES OF CYRENA. BY II. NYST. 



The species of this genus formed by Lamarck at the expense of 

 Cyclas of Bruguiere, and belonging like those to his Conchiferes di- 

 my aires lamellipcdes , are all inhabitants of rivers. They are at pre- 

 sent all exotic, but formerly they must have been widely spread 

 through Europe, since they are found in a fossil state with Melaniee, 

 Melanopsides, and Paludince, in layers of considerable extent : such 

 is, amongst others, the Cyrena semistriata, Desh., which we have 

 discovered in abundance at Kleyn Spauwen, near Maestricht, and 

 which is figured in our " Inquiries on the Fossil Shells of Housselt 

 and of Kleyn Spauwen," PL III. fig. 13. 



The genus Cyrena has been subdivided by Lamarck into two 

 sections, the one containing the species with lateral serrulated 

 teeth, of which Megerle afterwards made his genus Corbicula ; the 

 other comprehending those with entire teeth, which constitute the 

 genus Pridonta, established by Schumacher. The shell under con- 

 sideration belongs to the first of these sections. It should take its 

 place by the side of the Cyrena cor, Lamk., if indeed it be not its 

 fossil representative. 



Cyrena Duchastelii, Nob. — Testa cordata, subsequilatera, tumida ; 

 scalariter sulcata ; natibus fere conjunctis. 



Shell cordiform, nearly equilateral, thick, probably grooved, 

 traces of grooves visible towards the hinges in the injured speci- 

 men which we have before us. The hinges are very near each 

 other. 



We dedicate this epecies to M. F. Duchastel, who was so obliging 



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