30 



MEDUSA. I. 



western stations of this expedition, these stations being situated too far from land; on the other hand, 

 it was found on all of the eastern stations, stat. i, 2, 4, and 17. But in these localities, all in compara- 

 tively short distance from land, the species was found down to the very greatest depths, in which 

 hauls were made, and by no means in small numbers. Particularly interesting is the station 17 in the 

 deep channel between Rockall and Scotland; at this station 9 specimens were taken at the surface, 

 7 specimens in about 800 m depth, and a number of specimens about 100, 400, and 650 m below the 

 surface. On this locality, accordingly, the species was fairly common in all strata, at least as far down 

 as about 800 m below the surface. 



Yoimg specimens are, however, found in the upper water layers exclusively, whereas large and 

 middle-sized individuals may be met with in all depths. In the material at my disposal young indi- 

 viduals are present from the following localities: 



Loc. Nr. I. "Thor" stat. 45 (08). July 2nd 1908. Surface. — i specimen, 12 mm. 



— - 18. — — 11(08). May 28th 1908. About 40 m depth. — 9 specimen.?, 8—22 umi. 



— - 20. — — 8(08). May 27th 1908. About 40 m depth. — 7 specimens, 7— 16 mm. 



— - 21. — — 2 (08). May 2ist 1908. Surface. — 2 specimens, 6—13 mm. 



— - 26. Horns Rev. September 23rd 1912. 30—0 m. — i specimen, 5 mm. 



These localities are all .situated very near land. It will be observed, moreover, that most of the 

 young specimens have been found at the end of May; one specimen was taken at the beginning of 

 July in Faxebugt on the west coast of Iceland, and one .specimen, the smallest which I have seen, 

 was found in September off the west coast of Jutland. — Larger individuals may also be met with 

 early in the year. Thus on May 28th 1908 (Loc. Nr. 15) a specimen, 26 mm wide, was found in about 

 200 m depth, and the very largest among the specimens observed, 37 nmi wide, was found together 

 with 7 other .specimens on June 26th 1903 east of the Orkney Islands ("Michael Sars" stat. 140(03), 

 depth not stated). Most of the large specimens were, however, taken in July and August. This 

 agrees very well with the statements in the literature. According to these the species appears off the 

 British coasts in May, more seldom in April (Valencia Harbour, Browne 1900), is common during the 

 summer months, and disappears in October or November. The material, examined by me, gives no 

 information as to how late in the autumn the species may be met with in the area investigated, be- 

 cause none of the expeditions, the material of which has been at my disposal, has worked in these 

 regions later than in October, most of them only during the summer months. 



According to the above statements Laodicea undulata is, in the North-East Atlantic area, a 

 summer form, deliberated from the littoral hydroid Citspidella in the spring or the first summer months, 

 reaching its full size in the warm months, and disappearing in the late autumn, after having accom- 

 plished its breeding season; probably the planula larvae attach themselves in the autumn and develop 

 into the hydroid Cuspidella, which passes the winter and sends out its medusa generation in the 

 next spring. 



Also off the east coast of North America Laodicea undulata is a summer form, occurring from 

 June to the beginning of the winter, being most frequent in July and August. — In the Mediterranean, 

 on the other hand, it is found during the winter. 



