ABSTRACTS OF MEMOIRS. 519 



other oceanic species. In the region of the Flemish Cap the neritic 

 species were found spreading out more irregularly to the eastward, to a 

 considerable distance outside the Cap, their distribution between the 

 latter point and the eastern edge of the Banks being nmch confused with 

 that of the oceanic species. Here also the hydrographic limits of the 

 neritic species were about 34-50 and 5°, though the isohalines and 

 isotherms were very irregular in this region. The southern boundary of 

 the neritic species referable to the Labrador water could not be definitely 

 ascertained, but so far as the investigations extended they were found 

 to be confused with oceanic species along a line between Cape Race 

 and the south-eastern border of the Banks from April onwards. 



In the beginning of July, the seaward boundary of the neritic species, 

 north of about 50° N., showed only a slightly more w^esterly position 

 than was observed in the middle and latter part of June. The most 

 important change during this month concerned the entire disappearance 

 of the neritic Diatoms from the surface water of the northern half of 

 the Banks, and for some distance outside their northern edge, the species 

 being nowhere abundant south of 50*^ N. The Diatoms were found to 

 be superseded by an abundance of Peridinidse and other forms, notably 

 Tintinnidse, the species, however, including also Ceratium arcticwn, which 

 is generally characteristic of the true Labrador water though not con- 

 fined to it. These changes occurred concurrently with a general rise 

 ill the surface temperatures in this region to 6° and over, and a fall in 

 the salinities, at most points, below 3300. From several vertical series 

 of water samples which Mr. Matthews kindly obtained for me with the 

 water bottles during the working of his stations it was found, at all 

 points investigated on the Banks and a short way to the northward, that 

 the Diatoms were present in an underlying body of cold water, the upper 

 limit of their vertical range varying from 17 to 40 fathoms or more below 

 the surface. At a station off the southern end of the Flemish Cap these 

 conditions did not occur, and the dominating oceanic species Rhizosolenia 

 styhformis ranged from to 50 fathoms. 



A second point of importance observed in July concerned the zone 

 of transition between the two forms Ceratium arcticum on the north, and 

 C. longipes on the south. This was found occurring in the latitude of 

 Cape Race, and southwards to near the south-eastern border of the 

 Banks, in a region where in April, as has previously been stated, the 

 neritic Diatoms of the Labrador water were found confused with 

 Rhizosolenia stylifonnis and other oceanic species. C. longijjes was in 

 fact once recorded in April in the same region, in about 45° N. and 51° W., 



