290' bulletin: museum of comparative zoology. 



in the hauls on George's Bank (Station 10059). It was also notably 

 lacking in the Gulf Stream water (Stations 10064, 10071), except 

 for a few specimens at Station 10076 abreast of Chesapeake Bay. 

 Calanus appears to be uniformly rare, or absent, in the bays and sounds 

 of the southern coast of New England in summer: but it swarms in 

 Narragansett Bay in winter (Williams, 1906). Calanus was rare on 

 the surface, even in the Gulf of Maine, except at Stations 10085, 

 10093, 10096, 10097, 10100, 10101, and immediately off Gloucester, 

 July 8, where it swarmed at that level. Four of these stations were 

 occupied in daylight, three after dark; which shows that its absence 

 on the surface, in the regions where it swarms in deeper water, does 

 not depend altogether on sunlight, though the latter may be one of the 

 factors which confine it to deeper levels. And Calanus certainly did 

 not come to the surface off Cape Cod during the night of August 5, 

 for surface hauls, taken at 2 a.m., and at practically the same locality 

 at 8 A.M. (Station 10086), yielded very few Calanus, although the 

 deep haul caught thousands. Stations 10057, 10061, 10087, 10090, 

 10092, 10102, 10104 where hauls Avere taken at three levels, surface, 

 intermediate, and deep, show that Calanus was not usually equally 

 abundant at all depths, the yields of hauls at 15-20 fathoms being 

 very much larger than those at 50-85 fathoms. The numbers of 

 specimens per haul were far too large for counting; but the shallower 

 catches were usually two to four times as large in bulk as the deep 

 ones, a difference too great to be charged to the difference in mouth 

 area between the four foot and the Helgoland nets. And this source 

 of possible error was further checked by occasionally alternating 

 the two nets. The only exceptions to this rule were Stations 10093, 

 10097, and 10100, all in the eastern half of the Gulf, where Calanus 

 .was about equally abundant in deep and shallow hauls, i. c, just 

 the stations where it was abundant on the surface. 



Calanus finmarchicus was taken through a very wide range of tem- 

 perature, from about 42° (the deep hauls in the Gulf of Maine) to 

 76° (surface, Stations 10079 and 10080). But it was not abundant 

 in water warmer than 62° (surface hauls, eastern part of the Gulf of 

 Maine), and the great majority of the species was living in much 

 cooler water (42°-50°). The lowest salinity for Calanus was 31.8%o 

 (surface, Station 10103), the highest may have been as high as 35%o 

 (Station 10074, 20-0 fathoms haul). But it is by no means certain 

 that the specimens taken at that Station came from such salt water, 

 the net having passed through water as fresh as 33.2%. The vast 

 majority were living in water of 32.7%o to 33.4%o, in the intermediate 



