ECHINUS. 



153 



but not always, shut off from it ; three large tubercles often ou iuner 

 edge of each interradial. In the interambulacra there may be as many 

 as seventy plates, and on these a tendency may sometimes be observed 

 to carry alternately one and two large primary tubercles ; there is 

 typically a regular row of primary tubercles from pole to pole fringing 

 the poriferous zone, but with increase of size several of them may 

 become absorbed. The tubercles are rather larger and more closely 

 packed below than above the ambitus ; there are a moderate number 

 of secondary and miliary tubercles. The number of compound ambu- 

 lacral plates is about thirty, and they are covered by a number of 

 primary tubercles, of which there may be as many as six in a 

 rather irregular row ; there may be two irregular rows, and the 

 irregularity may be further increased by absorption of some of the 

 tubercles. No median bare space in eitber ambulacra or inter- 

 ambulacra, except in rare cases. Peristome rounded or pentagonal, 

 the membrane closely covered with plates bearing fine spines ; near 

 the mouth the spines are much stouter, and a large number of 

 pedicellariae are scattered among them. 



Distribution. East side of North Atlantic, North Sea, Mediter- 

 ranean ; Port Natal and John Adams Bank (Brazil). To 110 fms. 



a. Loch Etive, 15-20 fms. 



b. Tobermory, 30 fms. 



c. 4 miles S.E. of Sanda, 30-38 fms. 

 d, e. Between Sanda and Ailsa Craig, 24 fms. 

 f-k. Kilbrennan Sound, 10-20 fms. 



I,j. Loch Fyne, 80 fms. 

 A;, /. Between Great Cumbrae and Wemyss 

 Ground. 



m. West coast of Scotland. 



n. Belfast Bay, 20 fms. 



o. S.W. coast of Ireland, 50-00 fms. 

 p. S.W. coast of Ireland, 110 fms. 

 q-t. ? Galway Bay. 



u. Turbary, S. Ireland. 

 v, to. Off Liverpool. 



Xi Fishing-ground off Lundy. 

 y. Off Tenby. 

 z. Off Tenby. 

 «'. Ilt'racombe. 

 b'. Polperro. 

 c . Falmouth. 



Plymouth. 



Plymouth. 



Poole, 1\ fms., July 1889. 



Outside Portland Breakwater. 



Herm. 



Fern Islands. 



Firth of Forth. 



Firth of Forth. 



Montrose. 



Cromarty and Moray Firths. 

 n'-w". Moussa, [Shetland. 



John 

 John 

 John 

 J i ihn 

 John 

 John 

 John 



Murray, Esq. 

 Murray, Esq. 

 Murray, Esq. 

 Murray, Esq. 

 Murray, Esq. 

 Murray, Esq. 

 Murray, Esq. 



cV. 

 e'-ti. 



«"■/• 



k'. 



V. 



m'-p' . 



q'-s'. 



t'. 



h'-tn". 



Belfast Nat. Hist. & 

 Phil. Soc. 



Royal Dublin Soc. 

 Br. Grenfell. 



Dr. Bowerbank. 

 Br. Gray. 



W. P. Cocks, Esq. 

 C. Stewart, Esq. 



F. J. B. Beckford, Esq. 

 Rev. S. O. Ridley. 

 T. H. Powell, Esq. 

 W. Thorburn, Esq. 

 Br. Leach. 

 E. Forbes, Esq. 

 W. Duncan. Esq. 

 Dr. A. Sutherland. 

 E. M. Nelson, Esq. 



