1005 



GERVILLIA. 



GESNERACE.33. 



out without difficulty the peculiarities by which it may at once be 

 known. 



Cuvier, in his last edition of the ' Rogue Aniinnl,' places it under 

 Lcs Femes (Pa-no, of Bruguieres), between Crcnalula and Inoceramus. 



M. De Blainville arranges the genus under his family Maryaritacea 

 (the third of his Acephalof/iora Lamellibranchiata), between Pulvinites 

 and Aricuta. He notices that the shell gapes anteriorly, perhaps for 

 the passage of a byssus, and describes the ligament as multiple and 

 inserted in many conical fossae forming a row within the hinge. 

 lie also describes the abdominal impression as single, and as rather 

 anterior. 



Deslonchanips, speaks of the multiple ligament and the single some- 

 what oval muscular impression placed towards the middle of the 

 length of the shell and on the side of the dorsal edge, and remarks 

 that, like the Peiiias and other genera of the family Malleaceie, the 

 GervMice are covered externally with a delicate layer of fibrous 

 matter, and that they may b^ regarded as Perna with an articulated 

 hinge. The place assigned to them by M. Deshayes is between Penia 

 and Galillus. 



Mr. G. B. Sowerby observes that many species have occurred at 

 various geological periods from the Lias upward to the Baculite 

 Limestone of Normandy. M. De Blaiuville mentions, the species as 

 found in the department of La Manche. The genus occurs in the 

 Cretaceous Group (Greeusand), and largely in the Oolitic Group. 



GERVl'SIA (Zoology), a name given by Messrs. Quoy and 

 Gaimard to a genus of small Mollusks approximating nearly to 

 Plcuroltranchus. 



GESNERA'CE^E, Gcsnerworts, a natural order of Mouopctalous 

 Exogens, allied to Scrophvlariocees, and with them forming a portion 

 of the Dicarpous group. They are principally characterised by having 

 an ovary more or less inferior, and a parietal placentation. The leaves 

 are rugose, without stipules, generally opposite or whorled. Flowers 

 in panicles or racemes, seldom solitary. The calyx is half-adherent, 

 o-parted, with a valvate or open aestivation. The corolla monopetalous, 

 tubular, more or less irregular, 5-lobed, with an imbricated ie.stivation. 

 Stamens 2 or 4, didyuamous; anthers often cohering, 2-celled, innate, 

 with a thick tumid connective; the rudiment of a fifth stamen is 

 present. Ovary half-superior, 1 -celled, with 2 fleshy 2-lobud parietal 

 polysperrnous placentas placed right and left of the axis, surrounded 

 at its base by glands or a fleshy ring ; style continuous with the ovary ; 

 etigina capitate, concave. Fruit capsular or succulent, superior, 

 2-celled, with 2 opposite lateral placenta}, each consisting of 2 plates. 

 Seeds very numerous, minute ; embryo erect in the axis or fleshy 

 albumen, with the cotyledons much shorter than the radicle ; testa 

 thin, with very close fine oblique veins, sometimes extended into long 

 hairs, or even flattened into a wing. They iuhabit the hot and damp 

 parts of South America, and in some cases overrun trees with .their 

 rooting stems in the manner of ivy. The prevailing colour of their 

 flowers is scarlet ; some however are purple, as the Gloxinias, and 

 others pale-green, as Sinninyia and UryinonifL Many beautiful kinds 

 are known in our gardens ; and several other magnificent species are 

 figured in Von Martius's ' Nova Genera et Species I'lautarum,' vol. iii. 



loltnoidcl ; b, Gertillia ariculoidel. (1'ruin Suwciby's Genera.) 



M. Rang gives Gereillta a place under the Malleacece of Lamarck, 

 lietween Mallow nnd fnoceramia. In his description he notices the 

 Might anterior opening as being doubtless ('sans doute') for the 

 paaaage of a by 



M. Deshayes, in bin edition of Lamarck, 'notices the memoir of M. 



Leaves and flowers of Gcsno'a grandls, 



1, a corolla I.iiil open to show the interior; 2, a culyx, with the projecting 

 style ; 3, a transverse section of a capsule. 



