430 



BULLETIN OF THE BUREAU OF FISHERIES 



A. March 11, 1920, station 20066: 

 Diatoms not plentiful. 

 *Coscinodiscus asteromphalus 

 nant. 



11. — Georges Bank, east end 

 B. 



domi- 



♦Actinoptychus undulatus. 

 *Chretoeeras atlanticum. 

 *Ch. criophihnn. 

 *Ch. decipiens. 



Ch. densum. 

 *Ch. didymum. 

 *Coscinodiscus concinnus. 

 *C. excentricus. 

 *C. oculus-iridis. 

 *C. radiatus. 

 *Melosira sulcata. 

 *Rhaphoneis surirella. 

 *Thalassiothrix nitschioides. 

 B. April 16, 1920, station 20109, southeast edge 

 of bank. 



Diatoms very abundant. 

 *Chffitoeeras debile dominant. 

 *Ch. decipiens dominant. 

 *Ch. laciniosum dominant. 



*Chsetoceras atlanticum. 



*Ch. contortum. 



*Ch. criophilum. 



*Ch. densum. 



*Ch. diadema. 



*Ch. didymum. 



*Coscinodiscus asteromphalus. 



C. sp. 



April 16, 1920— Continued. 

 ♦Fragilaria oceanica. 



Lauderia glacialis. 

 *Nitschia seriata. 

 *Pleurosigma stuxbergii. 

 *Rhizosolenia semispina. 

 *Skeletonema costatum. 

 *Thalassiosira gravida, abundant. 

 *Th. nordenskioldi, abundant. 

 *Th. hyalina. 



*Thalassiothrix longissima. 

 *Th. nitschioides. 

 April 17, 1920, northeast part of bank, 

 station 20111 (fig. 122): 



Diatoms in medium abundance. 

 *Cha;toceras atlanticum. 

 *Coscinodiscus M dominant. 

 *Choetoceras decipiens. 

 *Ch. densum. 

 *Coscinodiscus concinnus. 

 *C. heteroporus (?) 

 July 23, 1914, station 10224: 



Diatoms abundant. 

 *Guinardia fiaccida dominant. 

 *Rhizosolenia shrubsolei notably abun- 

 dant. 



♦Actinoptychus undulatus. 

 *Cerataulina bergonii. 

 ♦Navicula gelida. 



Rhizosolenia semispina. 

 *R. styliformis. 



12. — Georges Bank, western end 



A. February 22, 1920, station 20046: 

 Diatoms abundant. 

 *Cha;toceras sociale dominant. 



*Actinoptychus undulatus. 



Cha;toceras atlanticum. 

 *Ch. criophilum. 



Ch. decipiens. 

 *Coscinodiscus crassus. 

 *C. subbulliens. 



Eucampia zodiacus. 

 ♦Guinardia flaccida. 



Leptocylindrus sp.? 

 *Navicula gelida. 

 *Nitschia sp.? abundant. 

 ♦Rhizosolenia imbricata. 



B. May 17, 1920, station 20128: 



Diatoms few on surface, abundant at 

 20 meters. 

 *ChaHoceras sociale dominant. 



♦Chaetoceras atlanticum. 



*Ch. decipiens. 



*Coscinodiscus concinnus. 



*C. subtilis. 



*Navicula gelida. 



*Pleurosigma normanii. 



*Thalassiosira decipiens. 



*Thalassiothrix longissima. 

 ,s "fully 50 per cent of the diatoms are an intermediate form between C. asteromphalus and C oculus- 

 ina!s, having t^e contxfty and leolation o, the former and the fineness and genera, delicacy of the latter. Indeed, Rattray and 

 others look on C. oculus-iridis as not a valid species." 



