504 Proceedings of the Royal Irish Academy. 



Gihhula magus (Linne). [Trochus magus, Jeffreys, B. C.) 



i., ii., iii., iv., v., vi. 



Generally distributed in the littoral and laminarian zones. 

 Distribution. — Sweden and Shetland to Mediterranean. Azores. 

 Madeira. Canaries. Senegal. C. Yerd I. 



Gihhula cineraria (Linne). {Trochus cinerarius, Jeffreys, B. C) 



i., ii., iii., iv., v., vi. 



Common everywhere on stones, &c., in the littoral and laminarian 

 zones. 



Distrihution. — Iceland. Finmark to Mediterranean. 



Gihhula tumida (Montagu). {Trochus tumidus, Jeffreys, B. C.) 



i., ii., iii., iv., v., vi. 

 Generally distributed in the laminarian zone and deeper water. 

 Distribution. — Finmark to Mediterranean. 



Gihhula umbilicata (Montagu). {Trochus umhilicafus, Jeffreys, B.C.) 



i., ii., iii., iv., v., vi. 



Very common on rocks, sea-weeds, &c., between tide-marks. 

 Distribution. — Hebrides to Mediterranean. 



Circulus striatus (Philippi). {Trochus Duminyi, Jeffreys, B. C.) 



i., . . . . vi. 



i. Portrush, one specimen (Marshall, f. Miss A. "Warren, '93). 

 vi. Bartra, Killala Bay, one imperfect specimen (Miss A. "Warren, '92) : 

 Bundoran (Waller and Jeffreys, f. Jeffreys, '65 ; Miss A. 

 "Warren, '93): "Porcupine" Exp., 1869, Donegal Bay, 25-40 

 fms. (Jeffreys, '83). 

 Distribution. — Ireland to Mediterranean. Morocco. 



Margarita helicina (Fabricius). {Trochus helicinus, Jeffreys, B.C.) 



i., ii., . iv., v., . 



i. Portrush (Marshall, '98) : off Ballycastle, dead (Chaster, '97a) : 

 Larne (Thompson, '56): Belfast Lough (Thompson, '56; living, 

 common, Hyndman, '58) : Turbot Bank, dead (Hyndman, '58) : 

 Groomsport (Marshall, '98 ; "Waller Coll. in Dublin Mus.) : 

 Strangford Lough (Thompson, '56) : Newtownards, Strangford 

 Lough, living (Praeger), Var. fasciata, Jeffreys. JS'orth of 

 Ireland (Hyndman, f. Jeffreys, '65) : Portrush (Marshall, '98). 



