86 



MEDUSA. I. 



values found. According to the table a difference between the East- and West-Atlantic specimens seems 

 actuallv to exist with regard to the quantity —^ in so far as the average value as well as the extremes 

 of the series of variation are distinctly lower as far as the specimens from the two western areas are 

 concerned than in the case of the specimens from the three eastern areas. That means that the 

 marginal vesicles are placed somewhat nearer to the radial canals in the specimens from the western 



Atlantic than in the specimens from the 

 eastern Atlantic area. The standard deviations 

 are, however, so large that we cannot state 

 at present, whether this result rests on a real 

 fact or whether it is merely casual. 



Distribution and Occurrence. 

 Tiaropsis nmlticirrata has a fairly wide 

 distribution in the North-Atlantic area. Its 

 occurrence is distinctly neritic. 



It is very common at the Atlantic coast 

 of North-America from Eastport to Cape 

 Cod (L. Agassiz 1849, A. Agassiz 1865, 

 Bigelow 1912, 1914 a, 1915). Within that 

 region it occurs during the spring from March 

 to May or the beginning of June. It is met 

 with only occasionally south of Cape Cod, 

 penetrating as far as Woods Hole (Nutting 

 1901, Hargitt 1902 and 1904). 



At the west coast of Greenland Tiaropsis 

 vmlticirrata has been found on several locali- 

 ties near the shore (see chart X), as far north- 

 wards as Egedesminde (loc. 3). With regard 

 to the occurrence on loc. 4, 5, and 6 (the 

 stations of the "Tjalfe" expedition) I shall 

 make the following remarks: On stat. 221 

 (loc. 4), August 28th 1908, a specimen was 

 taken about 50 m below the surface; in an adjacent place the temperature of the water was found to 

 be evenly decreasing from 4°.78 at the surface to o°.63 near the bottom (128 m); about 50 m below the 

 surface the temperature was about 2°, the salinity about 33 %o- In 1909 the species was found on July 

 2nd and 8th very near the shore in the neighbourhood of Frederikshaab (stat. 509 and 519), at both 

 occasions in large numbers and in water of low, though positive temperature. On stat. 509 (depth 

 265 m) 18 specimens were found about 60— 65 m below the surface; the temperature was: in 50 ra 

 o°.42, in 75 m o°.i4, the salinity was 32.5— 33 °/oo- On stat. 519 (depth 406 m) several hundreds of speci- 

 mens were taken at the surface at a temperature of o°.83; in 10 m depth the temperature was -^- o°.io, 



Jint. 50 



iOO 



jyo riifau and ^aei^oe Jsla n^^J 

 Jcela.nci 



S rce. rvia net 



3S0 



— I — I I 1- J/eu ToundlancL 



Fig. 15. Tiaropsis nnilticirrata Sars. Curves showing correlation be- 

 tween the diameter of the specimens and the number of tentacles 

 within different geographical areas. 



