ZOOLOGY AND BOTANY, MICROSCOPY, ETC. GH5 



others to the conclusion that the genera Palmella, Protococcus, and 

 Pleurococcus are simply phases in the cycle of development of higher 

 algas. 



Division of Closterium intermedium.* — J. Schaarschmidt de- 

 scribes the mode of division of this desmid as analogous to that of 

 Pentium interruplum. It has a primary suture, and a secondary suture 

 in the middle of each hemicyst ; and these present structures similar 

 to the caps of (Edogonium. Before each division the cuticle is raised 

 from the cell-wall in the form of a ring hollow on the inside, which 

 splits on division, while the very plastic cell- wall rapidly stretches. 

 The number of secondary and tertiary sutures, &c, may be very con- 

 siderable, the author having noticed as many as twenty-four rings, 

 indicating the number of times that the individual divides. He 

 believes that all other species of Closterium with secondary sutures 

 divide in the same way. 



Diatoms from the Island of Lewis. — Mr. E. W. Burgess sends 

 the following list made from the examination of a diatomaceous 

 deposit, new to Great Britain, from the island of Lewis, near 

 Stornoway, which he thinks may be of interest to those working out 

 similar deposits. It was found in the possession of J. Thompson, 

 who was using it to polish sections of corals. The list has been 

 submitted to Dr. Stolterfoth, of Chester, for verification of most of 

 the species. 



Abbreviations : — vr. (very rare), signifies that only one or two valves 

 have been found ; r. (rare), about one on each slide ; c. (common), 

 three or four on a slide ; vc. (very common), the form most often met 

 with on the slides. Prof. H. L. Smith's arrangement has been 

 followed. 



Tribe 1, Eaphidieae. Family 1, Cymbellese. Cymbella helvetica 

 Ktz. c. ; G. maculata Ktz. r. ; G. scotica W. Sin. c. Family 2, 

 Naviculere. Mastogloia sp. vr. ; Stauroneis anceps Ehr. r. ; S. Pliceni- 

 centron Ehr. vr. ; S. punctata Ktz. vr. ; Navicula (including Pinnu- 

 laria) ; N. angustata W. Sm. c. ; N. acuta W. Sm. c. ; N. firma Ehr. ? 

 vr. ; N. Hebes Balp. c. ; N. interrupts W. Sm. r. ; N. gibba Ehr. r. ; 

 N. major Ehr. r. ; N. ovalis W. Sm. vr. ; N. rhomboides Ehr. vc. ; N. 

 viridis W. Sm. c. ; N. viridula W. Sm. vr. Family 3, GomphonemeEe. 

 Gomphonema acuminatum Ehr. c. *, G. capitatum Ehr. vr. • G. con- 

 strictum Ehr. vr. ; G. intricatum Ktz. r. Family 5, Cocconidea3. 

 Cocconeis placentula Ehr. vr. ; C. Thwaitesii W. Sm. vr. 



Tribe 2, Pseudo-Kaphideaa. Family 6, Fragilarieas. EpitJiema 

 gibba Ktz. vc. ; E. proboscidea W. Sm. c. ; E. ocellata Ktz. c. ; 

 E. rupestris W. Sm. c. ; E. sorex Ktz. c. ; E. turgida W. Sm. r. ; 

 E. zebra Ktz. r. ; Eunatia diadema Ehr. vr. ; E. tetradon Ehr. c. • 

 Mimantidium arcus W. Sm. vc. ; H. bidens Ehr. vc. ; H. undulatum W. 

 Sm. r. ; H. majus W. Sm. vc; Synedra splendens var. danica 

 O'Meara J. D. vr. Family 7, Tabellarieae. Tabellaria fenestrata 

 Ehr. c. Family 8, Surirellese. Tryblonella angustata W. Sm. r. • 



* Magyar Novenytani Lapok, 1881. See Hedwigia, xxi. (1882) p. 92. 



