MEDUSAE. I. 87 



whence it was slowly increasing towards the bottom. - The occurrence of Tiaropsis multicirrata in 

 the Greenland waters must, probably, be regarded from the point of view, that the species is strictly 

 neritic and, therefore, does not occur in the Atlantic water-masses in the deep parts of the Davis Strait, 

 being restricted to the coastal regions where the water is very cold during the main part of the year, 

 except in the deeper strata in certain fjords. Not until rather late in the summer, when the effects of 

 the Polar Current are comparatively slight, and the surface of the sea is lighted by the sun during 

 the greater part of the twenty-four hours, the upper water layers attain a tolerably high temperature. 

 In agreement herewith Tiaropsts, which disappears from the coasts of New England as early as in 

 May, occurs at the Greenland coasts in the middle of the summer. Most of the individuals found are 

 large, mature or near maturity; probably the young specimens live in the deeper, warmer strata in 

 the fjords earlier in the summer. The fact that the species occurs in this area in the warmest part of 

 of the summer, while in other regions it is found in the spring, and the fact that it has not hitherto 

 been found in water of negative temperature, agree very well with our knowledge of the occurrence 

 of the species in other regions, viz. that it is a boreal species and avoids warm as well as ice-cold water. 



Tiaropsis multicirrata has a fairly wide distribution at the coasts of the British Isles, but no- 

 where it seems to occur in any great abundance. It has been found at the Shetland Islands ^Thau- 

 mantias melanops", Forbes), in Cromarty Firth (" Tiaropsis oligoplocamd\ Romanes), west-coast of Scot- 

 land, Port Erin, Belfast on Ireland ^Thatunantias patter sonii" Greene), Valencia Harbour, Falmouth, 

 and Plymouth ; in the southern of those places it has only been found occasionally. - - The data re- 

 garding the seasons of the finds demonstrate that the species appears at the British coasts in the 

 early spring, at the end of March, and disappears in May, seldom as late as in June. Browne (1895, 

 1900, 1905 a) has found quite young specimens at the end of March and in April in Firth of Clyde, at 

 Port Erin, and at Valencia Harbour. 



Tiaropsis imilticirrata has been found at Heligoland by Bohm (1878, p. 184, in great abundance 

 in April, never in the summer) and by Hartlaub (1894, p. 192, from March 3rd to April I2th, being 

 most common at the end of March). 



It seems to be a regular visitor to the Danish waters in the spring; it has frequently been 

 found in the northern part of the Kattegat, and in May 1915 I found some few specimens in Lillebelt. 

 The Danish finds are altogether from the end of April and the first half-part of May; large specimens 

 have been taken in the middle of May. 



We know very little about the distribution of Tiaropsis multicirrata along the coast of Norway. 

 M. Sars (1835) found it in the neighbourhood of Bergen; moreover it has been found at Kalvaag 

 south of Stat in June 1903 (loc. 3, also mentioned by Broch 1905, p. 7). 



It occurs in the Barents Sea (Linko 1900 and 1904 b), most commonly in the eastern part be- 

 tween Kanin and Kolguev Island; in the western part of the Barents Sea it is met with only oc- 

 casionally. 



Near Trangisvaag on the Faeroe Islands some few specimens were found by the "Ingolf" ex- 

 pedition at the beginning of May 1895 (loc. 20). 



The occurrence at the coasts of Iceland is peculiar. As will appear from the above list of 

 localities, Tiaropsis multicirrata has been found on several Icelandic localities, all of which are on the 



