LAMELLIBRANCHIATA. 



The specimens from deep water are more or less thin-shelled and of small dimensions; of those 

 from 170 fm. and more the largest specimen is 11.5"'"' long. Some of the many shells from St. 86, 87 

 and 98 belong to the variety acjilcata. 



Besides, the tendency of the species to vary is shown in a remarkable power of changing 

 sculpture and form according to the substratum, possessed not only by the valve which is 

 closely adherent to the substratum but also by the free, upper valve. Thus a specimen on Rctepora 

 has a pitted surface on the uj^per valve, where the pits correspond to the openings in the network of 

 the Bryozoa; a second specimen shows spinous ribs corresponding to the costce of the Pcctoi scptcin- 

 radiatus to which it is attached; a third on a spine of a Cidaris shows folds or wrinkles corresponding 

 to the longitudinal ribs of the spine; a fourth specimeu attached crossways on a Scrpitla tube has 

 sharp ridges opposite the rings of the tube, and so on. The contour of the shell is as a rule circular, 

 but sometimes the length is considerably greater than the breadth or the reverse or the contour 

 becomes very irregular according as the substratum restricts the growth in the one or other direction. 



Iceland. 



In addition to the specimens from the "Ingolf" stations, Auoiiiia sqiia inula has been taken at 

 Iceland in recent years at other places, east, north, west and south, as is shown by the following list. 



Eastlceland: 

 Myre Bugt 26 fm. 7 spec, and 10 valves. 



— ■- 36 - I — 



L,6nsvik 40 - , mud and clay. i valve. 



64°27'N. L., i3°27'W. L 84 - Many spec, on Balaiins Haincri. 



The Horn N. 74 E. 9 miles .... 38 - 2 spec. 



64°58' N. L., i3°25' W. L 40 - 3 valves. 



Faskrudsfjordr 50—20 - , blue clay. i — 



Reydarfjordr 14 - 2 .spec. 



Vidfjordr 8—12 - 6 valves. 



Nordfjordr 40 - i — 



Seydisfjordr at Skulavig 6 - i spec, and 18 valves. 



— - - 30 - 3 - 



Bakkafjordr 12—15 - , black sand. i valve. 



— 20—28 - , sand and clay. i spec. 



— 32—25 - , sand and clay vith shells. 3 valves. 



The largest specimen measures 15.5""". 



North Iceland: 



66°32' N. L., I5°i5' W. L 75 f™- i .spec, and 2 valve.s. 



Thistil Fjordr 10 - 2 — on algse, 3 spec, on Cy- 



priiia and 9 spec. 



— — 50-1 clay vith stones. i valve. 



