( 6 ) 
PART 
^18. — On the Cell -structure of Griffithsia setacea {JEllis), and on the Development of its' 
Antheridia and Tetraspores. By Edward Peuceval Wright, M.A., M.D. 
F.L.S., F.R. C.S.I. ; Professor of Botany in the University of Dublin. (With 
Plates XII. and XIII.) 
19. — On the Formation of the so-called Siphons," and on the Development of the 
Tetraspores in Polysiphonia. By Edward Perceval Wright, M.A., M.D 
F.L.S., F.E.C.S.I. (With Plate XIY.) Price 2s. 6(?. 
20. — On the Equations of Circles (Second Memoir). By John Casey, LL.D., F.R.S., 
M.R.I. A., Professor of Mathematics in the Catholic University of I'"^!""'' 
Price 3s. 6d. 
21. — On the Correlation of Lines of Direction on the Earth's Surface. By i 
P. O'Eeilly, C.E., Professor of Mining and Mineralogy, Eoyal CoU 
Science, Ireland. Price Is. 
22. — Explanatory Notes and Discussion of the Nature of the Prismatic Forms of a ip 
of Columnar Basalts, Giant's Causeway. By Joseph P. O'Eeilly, 2. 
Central School of Paris ; Professor of Mining and Mineralogy, Eoyal CoUege of 
Science, Ireland. (With Plates XV. to XVIII.) [Title-page and Table of Con- 
tents to Volume XXVI.] Price 5s. 
Transactions, Vol. XXVII. (Polite Literature and Antiquities.) 
1. — On the Belief St. Patrick, called the Clog an Edachta. By William Eeeves, D.D. 
Price Is. 
2. — On an Ogham Inscription. By Eight Eev. Charles Graves, D.D., M.E.I. A., 
Lord Bishop of Limerick, &c. (With Plate I.) Price Is. 
3. — On the Croix Gammee, or Swastika. By Eight Eev. Charles Graves, D.D., 
M.E.I. A., Lord Bishop of Limerick, &c. (With Illustrations). Price Is. 
4. — Fasciculus of Prints from Photographs of Casts of Ogham Inscriptions. By Sir 
Samuel Ferguson, LL.D. (With Plates I.* to V.) Price 2s. 
5. — On Sepulchral Cellse. By Sir Samuel Ferguson, LL.D. Price Is. 
6. — On the Patrician Documents. By Sir Samuel Ferguson, LL.D. Price 3s. 
7. — On the Stowe Missal. By Eev. B. Mac Carthy, D.D. Price 4s, (With Plate VI.) 
8. — On a Syriac MS. belonging to the Collection of Archbishop Ussher. By Very Eev. 
John Gwynn, D.D. [Title-page and Table of Contents to Volume XXVIL] 
Price 2s. 
Transactions, Vol. XXVIII. (Science.) 
1. — On Chemical Equilibrium. By Francis Alexander Tarleton, LL.D., Fellow 
and Tutor, Trinity College, Dublin. Price Is. 
2. — On a New Genus and Species of Sponge with supposed Heteromorphic Zooids, By 
Edward Perceval Wright, M.A., M.D., F.L.S., Professor of Botany in the 
University of Dublin. (With Plate I.) Price Is. 
IK 
