The Fresh-water Sponges of Ireland. 131 



Figc 3. Ephydatia flziviatilis, Autt, From Raheny ponds, Co. Dublin. — a. 

 skeleton-spicules ; b. amphidiscs (gemmule-spicules). 



Fig. 4. Ephydatia Mulleri, I^ieberklihn. From McHugoIsland, Lough 

 Rea, Galway. — a. smooth skeleton-spicule ; b. spined skeleton-spicule ; 

 c.,d. amphidiscs ; e. rotule of amphidiscs. (Figs, c, d., e., copied from 

 Bowerbank, I. vol. III., pi. LXXXVL, figs. 14, 11, 12). 



Fig. 5. ? Ephydatia crateriforniis. Potts. From Park Lough, Hungry 

 Hills. — a. skeleton-spicules; b. immature (?) amphidiscs; c. mature 

 amphidiscs. (Fig. c, copied from Potts 7, pi. v, fig. 5/^) 



Fig. 6. Heterojiuyenia Ryderi, Potts. From Lough Doon, near Dingle. — 

 a. skeleton-spicules ; b. short amphidiscs ; c. long amphidiscs ; d. 

 immature (.?) forms. 



Fig. 7. Tubella pennsylvanica. Potts. From Columbkille Lough, Bally- 

 shannon. — a. skeleton-spicules, one of them with pointed, the others 

 with rounded ends ; b. amphidiscs. (Fig. b, copied from Potts, 7, 

 pi. xn., fig. i^). 



THE ORIGIN OF MKGACEROS-MARL. 



BY CLKMKNT RBID, F.LS., F.G.S. 



Through the kindness of Mr. W. Williams of Dublin I have 

 lately had an opportunity of examining a sample of the marl 

 from which he has obtained skeletons of Cervus giganteus 

 {inegaceros?) The exact locality is not mentioned, but Mr. 

 Williams informs me that he " does not think that there is any- 

 thing exceptional in the place which the clay came from, as 

 the bogs are spread over a good many miles of country, and 

 are all of the same character on the central limestone plain 

 of Ireland, about 120 miles from Dublin." As a minute 

 examination of this marl has suggested a new explanation of 

 the mode by which the deer were trapped in such quantities, 

 I think that it may be interesting to give the results, not 

 committing ourselves, however, to any opinion as to the 

 partial or general application of this explanation. Until an 

 examination of a larger series of specimens can be undertaken 

 it will be impossible to say whether the peculiar conditions 

 may not be confined to a single locality, and that elsewhere 

 the deer were merely bogged in the way suggested by Mr. 

 Williams in his paper published in 188 1'. 



■" W. Williams. — " On the Occurrence of Megaceros Hiberniciis, Owen, in 

 the Ancient Lacustrine Deposits of Ireland ; with Remarks on the 

 Probable Age of these Beds." Geol. Mag. (new sen), Dec. XL, Vol. VIIL, 



PP- 354-363- 



