54 



THE HANCOCK PACIFIC EXPEDITIONS 



VOL. 3 



Corethron criophllum Castr. 



Coscinodiscus spp. 



Dactyliosolen sp. 



Ditylum brighuvelli (West) 



Eucampia zoodiacus Ehr. 



Guinardia flaccida (Castr.) Perag. 



Hemiaulus hauckii Grun. 



Leptocylindrus danicus CI. 



Lithodesmium undulatum Ehr. 



Navicula spp. 



Nitzschia longissima (Breb.) Ralfs. 



seriata CI. 

 Planktoniella sol (Wallich) 



Rhizosolenia alata Btw. 



calcar avis Schultz 



delicatula CI. 



fragilllsima Berg. 



semisplna (Hansen) Gran 

 Rhizosolenia setigera Btw. 



stolterfothii H. Perag. 



styliformis Btw. 

 Skeletonema costatum (Grev.) 

 Stephanopyxis sp. 

 Thalassionema nitzscioides Grun. 

 Thalasslosira condensata CI. 



decipiens (Grun.) 



rotula Meunier 

 Thalassiothrix frauenfeldii (Grun.) 



heteromorpha ( .'' ) Karst. 

 longissima CI. & Grun. 



Corethron criophilum Castr. 

 Coscinodiscus spp. 

 Dactyliosolen sp. 



Eucampia zoodiacus Ehr. 

 Guinardia flaccida (Castr.) Perag. 

 Hemiaulus hauckii Grun. 

 Leptocylindrus danicus CI. 

 Lithodesmium undulatum Ehr. 

 Navicula spp. 

 Nitzschia longissima (Breb.) Ralfs. 



seriata CI. 

 Planktoniella sol (Wallich) 

 Pleurosigma sp. 

 Pseudoeunotia doliolus (Wall.) 

 Rhizosolenia alata Btw. 



calcar avis Schultz 



delicatula CI. 



fragilllsima Berg. 



semisplna (Hensen) Gran 

 Rhizosolenia setigera Btw. 



stolterfothii H. Perag. 



styliformis Btw. 

 Skeletonema costatum (Grev.) 

 Stephanopyxis sp. 

 Thalassionema nitzscioides Grun. 

 Thalasslosira condensata CI. 



decipiens (Grun.) 



rotula Meunier 

 Thalassiothrix frauenfeldii (Grun.) 



heteromorpha (.'') Karst. 

 longissima CI. & Grun. 



An interesting point in respect to occurrence of species is the rela- 

 tively high abundance of a species not yet satisfactorily named at 

 the Scripps Institution, although it has been seen often in Institution 

 collections for nearly twenty years. For some years it was recorded 

 In Institution lists as Thalassiothrix acuta Karst, on the assumption 

 that it was enough like that species to carry the name without confu- 

 sion. More recently it has been decided to list It as T. heteromorpha 

 Karst. because Its characteristics are more nearly those of the latter 

 species. On a few occasions the form has reached large abundance 

 In oceanic catches, mostly in the Gulf of Santa Catalina off southern 

 California. But In all of those Instances it was associated with other 

 forms showing larger numbers. In mid-Gulf in this series, at a point 

 a little south of the latitude of Guaymas, a large catch (143,000 cells 

 per liter) was taken which consisted almost entirely of this species. 

 A moderately large catch (12,000 cells per liter) was obtained three 

 days later in Concepcion Bay and it was also nearly exclusive of 



