184 JOURNAL OF CONCHOLOGY, VOL. I4, NO. 6, APRIL, I9I4. 



Associated with it at Benbecula were other southern species — Diplo- 

 donta roiundaia, Cerithiopsis concate?iata, and on the shore Littorina 

 ohtusaia van ornata. Another interesting locaHty for this Httle 

 bivalve is the Japanese seas. 



L. clarkise Clark. — Rathlin Island, Antrim (Chaster) ; Sanda 

 Island 27f., Davar Island 26f., and Ailsa Craig 2']{. (Knight)! Caldy 

 Island, off Loch Ryan 25f., off Arran 6of., and Benbecula Sound lof. 

 Also Straits of Korea, 33"i5 N., i29"5 E., in lof. ('Sylvia')! The 

 supplementary figure in "British MoUusca" is perfect. 



L. obliquatum Monts.^ — S. W. Ireland, io-4of. (R.I. A. cruise); 

 Antrim (Chaster). 



Montacuta substriata Mont. — Straits of Korea 54f. ('Sylvia')! 



M. bidentata var. elliptica S. Wood, "Crag Moll.," vol. iii., 

 supp. tab. X., fig. 21 (as M. elliptica). — Proportionally longer from the 

 beaks to the front margin (being nearly as long as broad), larger, 

 equally rounded on all sides except where interrupted by the beaks, 

 which are nearer (almost overhanging) the posterior end. L. 0*125 ^"5 

 b. o'i5o. Scalloway (Simpson)! Guernsey, Donegal Bay, Killala Bay, 

 Achil. Also from Adventure Bank, Mediterranean, 92f. (' Porcupine ') ; 

 these latter are nearly circular in outline. The recent form of this 

 variety is more abnormal than the Crag one, and resembles the 

 young of Tapes aureus in shape. In outline it is still more like M. 

 ovata Jeff., an Atlantic species. Not Brown's Telliuiy a elliptica, which 

 is M. ferruginosa. 



var. triangularis Jeff. — Bantry Bay ; Benbecula. This is 

 possibly the M. truncata of Searles Wood. 



M. tumidula Jeff. — Straits of Korea 4of., 32-46 N., r28-59 E. 



M. ferruginosa Mont. — The umbones of this shell are frequently 

 capped, similar to the freshwater species Sphceriuin lacustre and 

 Pisidium henslowianum, mostly observable in the young. 



M. ferruginosa is not truly parasitic, but attaches itself to its host 

 for the purpose of sharing in its nutriment, though in some instances 

 it follows in its tracks for the purpose of acting the part of scavenger. 



The same conditions of habitat which I have observed in regard to 

 this species in Torbay and elsewhere" also obtain at Salcombe in 

 South Devon, but it seems to have escaped the observation of Colonel 

 Montagu, to whom Salcombe was a favourite collecting-ground, and 

 also of Canon Norman, who discovered Lepton squamosum on the 

 same ground commensal with a shrimp {Gebia stellata), but missed 

 \.\\e Montacutce, while, on the other hand, though I have frequently 



1 Lepton (NeoleJ'ton) ohligiiaUim Monts., Niio. Riv. Conch. Med., p. 12; Irish Naturalist, 

 July, 1897, p. 86, woodcuts. 



2 Habitat oi MoniactiiaJ'eri uginosa, Joiirit. 0/ Conch., 1891, vol. vi., pp. 399-404. 



