( 6 ) 
PART 
/18. — On the Cell- structure of Griffithsia setacea (.F^^u), and on the Development of its 
Antheridia and Tetraspores, By Edward Perceval 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., 
V F.L.S., F.E.C.S.I. {With Plate XIV.) Price 2s. ed. 
20. — On the Equations of Circles (Second Memoir). By John Casey, LL.D., F.R.S., 
M.H.I.A., Professor of Mathematics in the Catholic University of Ireland. 
Price Ss. 6d. 
21. — On the Correlation of Lines of Direction on the Earth's Surface. By Joseph 
P. O'Eeilly, C.E., Professor of Mining and Mineralogy, Eoyal CoUege of 
Science, Ireland. Price Is. 
22. — Explanatory Notes and Discussion of the Nature of the Prismatic Forms of a Group 
of Columnar Basalts, Giant's Causeway. By Joseph P. O'Eeilly, C.E. 
Central School of Paris ; Professor of Mining and Mineralogy, Eoyal College 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 Cellae. 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. 
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 XXVII.] 
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. 
