DESCEIPTION OF THE EXGEAYIXGS. 951 



cells, showing one segment the form of the germ-cell, the other, ordinary vegetative division 

 supervening, having assumed that characteristic of the species. 61. Euastrum didelta 

 (Ralfs), X 150, abnormal condition of, after W. Archer (Nat. Hist. Review, vi. p. 469), 

 showing a central irregular structure produced between the original segments, apparently 

 owing to the non-formation of a septum on the resumption of vegetative growth, and 

 forming with them but one uninterrupted cavity; and in tliis instance the new central 

 growth having assumed the size and nearly the form of an entu*e frond, its axis of growth 

 and plane of expansion are at right angles to the old segments. 62. Artlu^odesmus Incus 

 (Hass.), x300, abnormal condition of, after W. Archer, I.e., showing an abnormal growth 

 analogous to preceding, but carried on to another vegetative generation, the middle portion 

 being older than those produced between it and the original segments, the whole still 

 forming witliin but one uninterrupted cavity. 63. Cosmocladiimi pulchellum (Breb.), 

 X250. 



PLATE lY. (Diatoms). 



[Plates rV. to YIII. are engraved by Mr. TufFen West. Many of the figures are from original 

 drawings, others from specimens, and all of them are magnified 300 diameters.] 



Figure 1. Epithemia turgida, f. and s. v. 2. E. Westermanni. 3. Eunotia pentaglypliis. 

 4. E. triodon. 5. Amphicampa mirabilis. 6. Himantidium pectinale, f. and s. v. 7. 

 Podosphenia Eln-enbergii, f. and s. v. 8. Rhipidophora paradoxa. 9. Licmophora flabel- 

 •lata. 10. Podocystis Adriatica. 11. Sceptroneis Caduceus. 12. Dimeregramma sinu- 

 atum, f. and s. v. 13. Diatoma vulgare, f. and s. v. 14. D. elongatum. 15. D. Ehren- 

 bergii. 16. D. hyalinum, f. and s. v. 17. Asterionella formosa. 18. A. Ralfsii. 19. 

 Bacillaria paradoxa, f. and s. v. 20. B. cursoria. 21. Nitzschia Sigma. 22. N. scalaris, 

 f. and s. V. 23. Ceratoneis longissima, f. and s. v. 24. Homoeocladia Martiana, f. and s. v. 

 25. H. fiUformis. 26. H. sigmoidea. 27. Synedi'a Arcus, f. and s. v. 28. S. pulchella, 

 f. and s. V. 29. S. capitata. 30. Amphipleura pellucida. 31. A. inflexa. 32. Plagio- 

 gramma pulchellum, f. and s. v. 33. Dimeregi'amma nanum, f. and s. v. 34. D. distans, 

 f. and s. V. 35. D. Tabellaria, f, and s. v. 36. Trybhonella gracilis. 37. T. acuminata. 

 38. Campylodiscus Hibernicus. 39. C. spiraHs. 40. Striatella unipimctata, f. and s. v. 

 41. Rhabclonema minutum, f. and s. v. 42. Hyalosu*a delicatula, f. and s. v. 43. Rhab- 

 donema Crozieri, f. and s. v. 44. Biblarium Castellum (EM. 33. 2. 1.). 45. Stylobibliiun 

 Clypeus. 46. Gomphogramma rupestre, f. and s. v. 47. Grammatophora marina. 48. 

 G. serpentina, f. and s. v. 49. Gephyria media, f. and s. v. upper and imder valves. 

 50. G, incm*vata, f. and s. v. ditto. 51. Diatomella Balfouriana, f. and s, v. 52. Disi- 

 phonia australis. 



PLATE Y. (Diatoms). 



Figure 53. Cyclotella operculata, f. and s. v. 54. C. rectangula, f. and s. v. 55. 

 Actinogonium septenarium. 56. Liostephania magnifiea. 57. L. Rotula. 58. Dictyo- 

 lampra Stella. 59. Mastogonia Actinoptychus. 60. Hyalodiscus subtilis. 61. Podosira 

 Montagnei, f. and s. v. 62. Melosu-a Horologiima, f. and s. v. (EM. 33. 2. 17). 63. M. 

 8ubfle:alis, f. and s. v. 64. M. nummuloides, f. and s. v. 65. M. orichalcea. 66. Aste- 

 romphaliis Arachne. 67. Melosira Roseana, f. and s. v. 68. Discosira sulcata, f. and s. v. 

 69. Stephanodiscus ^gyptiacus, f. and s. v. 70. Endictya oceanica, f. and s. v. 71. Me- 

 losira Borreri, f. and s. v. 72. Liparogyra spiralis, f. and s. v. 73. Peristephania Eutycha. 

 74. Stephanopyxis Tm'ris. 75. S. ferox, f. and s. v. 76. Xantliiopyxis oblonga. 77. 

 Stephanogonia polygona, f. and s. v. 78. Coscinodiscus ovaHs. 79. Asteromphalus 

 Brookei. 80. Craspedodiscus Coscinodiscus. 81. Systephania Corona. 82. Halionyx 

 undenarius. 83. Coscinodiscus stellaris. 84. Actinocyclus Ralfsii. 85. Heterostephania 

 Rothii. 86. Asteromphalus Darwinii. 87. A. elegans. 88. Actinoptychus undulatus, 

 f. and s. V. 89. Coscinodiscus concinnus. 90. Odontodiscus eccentricus. 



PLATE VI. (Diatoms). 



Figure 1. Auliscus pruinosus. 2. Eupodiscus Argus : a, s. v. ; h, f. v. (the latter 

 from Kiitzing). 3. Auliscus sculptus : a, s. v. ; h, f. v. 4. Aulacodiscus Oreganus. 5. 

 A. Beeveriae. 6. Porpeia quadriceps : a, s. v. ; h, f. v. 7. Cerataulus Isevis : a, s. v. ; 

 h, filament. 8. Hych'osera compressa, s. v. 9. Cerataulus turgidus : a, s. v. ; 6, f. v. 

 10. Biddulpliia Tuomeyi: «, s. v. ; 6, f. v. 11. Zygoceros Mobiliensis: a, s. v. ; 5, f. v. 

 12. Biddulphia Indica. 13. Hydrosera triquetra : a, s. v. ; h, filament. 14. Hemidiscus 

 cimeiformis: <r, s. v. ; h, f. v. "^15. Triceratium Solenoceros. 16. T. exiguum. 17. T. 



