MUSHAM : MOLLUSCA OF lONA. 59 



of many of our land shells, twelve fine specimens of Helicella acufa 

 turning up in an old boot ! 



The chief object of my visit, however, was to obtain if possible 

 examples of the shell-necklaces, formerly sold here by the children 

 to visitors, an old custom dating from the time of the monkish 

 occupation of the island, shells and jade pebbles being in great 

 request as mementoes, and alluded to by Wordsworth in his sonnets. 



These necklaces are nowadays seldom made and therefore diffi- 

 cult to procure ; modern visitors preferring picture post cards and 

 articles of pebble and marble, sold here, but made elsewhere. The 

 necklaces were turned out in different sizes according to the shell 

 used, some entirely made of H. nemoralis, others of itala or aatt.t, 

 and again of all three together ; dead shells from the dunes were 

 mostly used, mixed with any live ones picked up at the time of 

 gathering, the animal not being removed. Mr. Welch informs me that 

 the necklaces made from Helicella itala differ from the Donegal 

 examples, in that these are threaded through the apex, and not 

 through the mouth and upper part of the larger whorl. 



It is noticeable that they are invariably made up with black 

 thread; on inquiring the reason, I was informed it was the custom, 

 though no reason for it was forthcoming. Marine shells (periwinkles) 

 would occasionally be used in the manufacture of these necklaces, 

 but, requiring boring before threading, were only adopted by the 

 more industrious. 



Mr. Somerville concludes his paper by stating that all his shells 

 were submitted to Mr. J. W. Taylor for verification, and adds, — 

 "lona consists chiefly of schistose rocks of the middle Silurian period. 

 It is one of the mid Hebrides (or central group of the inner Hebrides 

 which form tlie British Vice-County, No. 103), and which in addi- 

 tion to Mull, includes Coll, Tiree, Ulva, and in the words of Sir 



Walter Scott— 



' All the group of islets gay 



That guard famed Staffa round.'" 



The following is a joint list of observations: — 



Arion ater (L.). — Very large and abundant, referable to var. ater- 

 rima Taylor. Somerville, "our common black snail." 



A. bourguig^nati Mabille. — Somerville. 



Limax maximus L. — One or two near the Nunnery. 



Agriolimax agrestis (L.). — Pale forms abundant. Somerville, 

 "the common pale-brown slug." 



Limnaea pereger (MiilL). — Somerville, "common in a stream in 

 the middle of the island." 



Vitrina pellucida (Miill.).— Somerville. 



