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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1894 Excerpt:...Var, lanceolata Grun. (1860).--V. broadly lanceolate. Ends not rostrate. L. 0,04; B. 0,oie mm. Striae 7 to 8 in 0,o i mm.--N. tumida var. lanceolata Grun. Verb. 1860 p. 537 PL IV f. 44. A. D. p. 34. Brackish water: Sea of Kara! Skienitz See near Berlin (Grun.), Neusiedlersee (Grun.). Nav. Placentula is very nearly akin to Nav. Gastrum, and it is questionable whether they should not be united in one species. The median striae are in Nav. Gastrum, but not in Nav. Placentula, alternately longer and shorter, but this characteristic is subject to great variation, the var. Jenisseyensis having only a few, and the var. latiuscula no, shorter median striae. Of more importance is it that Nav. Placentula has coarsely lineate, or almost punctate striae. Nav. anglica is nearly akin to Nav. Gastrum and might be considered as a variety of it. There exists in fact no limit between these three species; Nav. Placentula appears to be akin to Nav. leptostigma, which has finer, distinctly punctate, striae and that to Nav. platystoma, the striae of which are very finely punctate. On the other hand N. Placentula is by its coarsely punctate striae allied to the section Punctatas, among which Nav. amphibola is nearly akin to Nar. Placentula. Smaller forms of Nov. Gastrum closely resemble smaller forms of Nav. peregrina var. Menisculus, from which they differ by the terminal striee being radiate throughout, but this characteristic is sometimes excedingly delicate. 32. N. leptostigina Ehb. (1854).--V. elliptical, with more or less broad, rostrate ends. L. 0,038 to 0,048; B. 0,ois to 0,02 mm. Axial area indistinct. Central area large, orbicular. Strise 14 in 0,oi mm., radiate throughout, distinctly punctate (puncta about 22 in O.oi mm.) in the middle alternately larger and shorter.--...