among the Shetland Isles. 299 



its congeners and companions^ all of which have very con- 

 spicuous eyes. It is a somewhat remarkable coincidence that 

 the shell of E. stenostoma resembles a large Achatina acicula 

 (a land mollusk), which is in the same category as regards 

 these so-called organs of sight. The shells of P. carinata and 

 P. nivalis are easily distinguishable. 



Among the rarer and more noteworthy mollusks procured 

 this year were the following : — 



Montacuta tumidula. St. Magnus Bay and near Fetlar. 

 Described by me from the Hebrides in the Reports of the 

 Association for 1866. 



M. donacina^ S. Wood. A single valve from deep water 

 in St. Magnus Bay. Another valve had been dredged by 

 me at Falmouth in 1839. It is a rare Coralline Crag fossil. 

 It nearest ally is M. suhstriata. 



Utriculus glohosusj Loven. A small living specimen oc- 

 curred again in St. Magnus Bay. 



U. expansus^ Jeffr. A few young specimens also in St. 

 Magnus Bay. 



Odostomia Warrenij Thompson. Never having seen this 

 shell in a fresh and perfect state, I considered it (Brit. Conch, 

 iv. p. 143) a variety of 0. ohliqua. But the discovery of live 

 specimens in St. Magnus Bay and near Fetlar enables me to 

 separate the two as distinct species. 0. Warreni has a 

 shorter spire and more swollen whorls than 0. ohliqua^ the 

 suture is deeper, the stride are much stronger at the base of 

 the shell, the whole surface is covered with most delicate and 

 close-set microscopic spiral lines, and the umbilicus is well de- 

 veloped and deep. The animal of 0. Warreni has a peculiar 

 foot ; this is not plain and rounded at its extremity, as in 

 0. ohliquay but is deeply bilobed or forked like the tail of a 

 swallow. No other species of Odostomia^ so far as I am aware, 

 has a similar foot. One individual spun a fine glutinous thread 

 from the middle of the sole of the foot, and kept itself suspended 

 for some time from the surface of the water, with the point of 

 the shell downwards. I found a dead specimen of 0. ohliqua 

 on the same ground with 0. Warreni. 



0. umhilicarisj Malm. A young specimen from St. Magnus 

 Bay, nearly globular, and thus exhibiting the same distinctive 

 characters as the adult. 



Siphonodentalium Lofotense and Cadulus (or Loxoporus) suh- 

 fusiformis again occurred, the former being more widely dis- 

 tributed. Both inhabit the Mediterranean ; and the latter is 

 a Sicilian and Viennese fossil. I had an excellent opportunity 

 of observing them alive and in active motion. The thread- 

 like and extensile organs by which the Solenoconchia seize 

 their prey are unlike the tentacles of any Gastropod, and their 



