LAMELL1BRANCHIATA. 



... 



Distribution. On the North American side Cyprina islandica occurs from Cape Hatteras to 

 the Newfoundland Bank and the southern part of the Gulf of St. Lawrence M. On the European side- 

 it is distributed from the south-west of France (Arcachon) to the Murman Coast and White S« 

 towards the west it reaches over the Faeroes to Iceland; from the Kattegat it reaches into the Sound 

 and through the Belts down into the south-western Baltic'). Cyprina islandica is consequently, as I 

 have already more fully shown on an earlier occasion 4), a distinctly boreal form, a result that 

 Prof. Brogger has also come to from a consideration of its late immigration into southern Norway'). 

 The vertical distribution is ca 4— 50 fin., but the young may be met with in greater depths 



In geologically very late (postglaciall deposits it has been found as far north as at Spitzbergen, 

 which indicates that the climate of that time was somewhat milder than it is now I. 



Remarks. Gould cc Binney write regarding Cyprina islandica (op. cit. p. 131): "It is subject 

 to very little variety". This does not agree with the experience I have gained on going through a 

 number of specimens from Iceland and the Fceroes. I find, that the three dimensions of the shell 

 may vary considerably, as will be seen from the measurements given below. 



Locality Length 



Reykjavik 105 """. 



Vestmanhavn JOJ-S - 



Keflavik 102.5 " 



Seydisfjordr 102 - 



Reykjavik 99 - 



Onundarfjordr 98.5 - 



Vidarvik 93 - 



Br< adth 

 Length 



58.6 



48.8 - 

 56.6 - 



5° - 



55.S - 



50.8 - 

 55-9 - 



') Posselt (I.e.) gives it from Labrador and Packard as his authority, hut it is not mentioned in the latters 

 "View of the recent Invertebrate Fauna of Labrador" (Mem. Boston Soe. Nat. Hist, vol.1, Part II. 1S67, p. 262 1, nor in the 

 later lists of the Molluscan fauna of Labrador by W. H. Dall and Katharine Bush. The northern boundary foi its occur- 

 rence at N. America is fixed, I find by the following statement of Whit eaves: "Although recorded by Fabricius 

 Greenland shell, this species has not yet been found in the Gulf of St. Lawrence, north of the Baie des Chaleurs" (Catal. of 

 the Marine Invertebrata of Eastern Canada, p. 130; Geol. Survey of Canada, 1901 |. W. is not right however in his reL 1 

 to Fabricius' Venus islandica (Fauna groenlandica, 17S0, p. 411), as this is obviously not identical with Li line's Venits 

 (Cyprina) islandica, but with Cardium (Serripes) groenlandicum Chemnitz. 



2 ) Cattie states, that it has also been taken in the eastern ithe "cold") part of the Murman Sea (Les Lamellibran 

 ches .... du "Willem Barents". Bijdragen tot de Dierkunde, 1SS6), hut Knipowitsch has never found it there (Zur Keunt- 

 niss der geol. Gesch. der Fauna des Weissen und des Murman-Meeres, p. 24. Verhandl. Kais. Russ. Mineral. Gesellsch. 

 St. Petersburg. 2. Ser., Bd. XXXVIII, No. 1), so that it must be in any case extremely rare. 



3) In his lists showing the distribution of the Mollusca taken by the Swedish Expeditions of [875 and [876, I 



has given C.islandica as occurring in the Bering Sea (K. Sv. Vet.-Akad. Handl. Bd. 16, X" 2, [878, p. 81), ami this statement 

 appears again in Posselt (I.e.); some mistake in writing or printing must have crept in here, as the species i-- not mentioned 

 in any of the lists published by Dall, Crosse, Edg. Smith or Krause on the Mollusca of the Bering Sea. 



4) Ad. S. Jensen: Studier over uordiske Mollusker. II. Cyprina islandica. Vidensk Medd. naturh. Foren. Kbhvn., 



IQ ° 2 , P-33- 



5) Brogger: Om de senglaciale og postglaciale nivaforandringer i Kristianiafeltet, 1900 -01, p. 573. 



6 ) A. C. Johansen has shown, that small (young) specimens can be met with even in the abyssal region, as J effrei s' 

 statement of the occurrence of C.islandica W. of Ireland down to 121.=, fm. refers to quite small individuals (Vid. Medd. 

 Naturh. Foren. Kbhvn., 1901, p. 44). 



7) Cf. my paper on Cyprina islandica 1. c and Jensen & Harder in: "Postglaziale Klimaveranderungen, Stockholm 

 1 9 1 o, p. 400. 



