214 



Part III — Fifteenth Annual Report 



into first place, far exceeding any other Clyde diatom ; Coscinodiscus con- 

 cinnus also became far more plentiful ; and both species of Chcetoceros, 

 named above, also increased greatly. There were numbers of other dia- 

 toms, now present, now absent, but these were the forms characteristic of 

 the season. In summer, while diatom life was scarcer, there was a much 

 greater variety of forms ; but only in the Sound of Mull and in Loch 

 Etive an approach to the quantities obtained in the Clyde in spring. 1 

 seut nine typical tubes to Professor Cleve, who has kindly favoured me 

 with the report on them in the accompanying table. 



x =dead fragments. rr = very rare. cc = very common. 



r = rare. c= common. += not rare. 





Sound of Mull, Tober- 

 mory. 



Sound of Mull, Tober- 

 mory. 



Sound of Mull, Barony 

 Point. Surface. 



Sound of Mull, Barony 

 Point. 5 fathoms. 



Rum to Ardnamurclian. 



Loch Nevis. 



Loch Hourn. 



Loch Etive. 



Loch Aber. 



Bacteriastrum varians, Laud., . 











x r 





x r 







Ceratatilina Bergonii, Per., 





x 





rr 



r 











Chcetoceros borealis, Bail., . 











r 



+ 



r 







,, commutatus, CI., 

 ,, constrictus, Gran, 



+ 



V 





r 



+ 







+ 



















r 





,, contortus, Schiitt, 



-fr- 









+ 



+ 





+ 





criophilus, Cast., 

 curvisetus, CI., 











r 











ee 



cc 



cc 



cc 



cc 





r 



c 



cc 



debilis, CI., 



+ 



c 



+ 





+ 









+ 



,, decipiens, CI., 



+ 



c 



+ 



+ 



+ 



+ 



c 



+ 





didymus, Ehr., . 



c 



r 



+ 



+ 



c 



+ 



r 



r 



+ 



,, diadema, Gran, . 



r 





+ 





r 











septentrionalis, Oestr., 











r 







r 





scolopendra, CI., 

















x r 





Coscinodiscus concinnus, W. Sm., 





r 



r 



r 



r 







r 



r 



,, excentricus, Ehr., . 











r 







r 



r 



,, radiatus, Ehr., 











r 





r 



r 



r 



Diiylum Brightwellii, Grun., 



r 









r 







r 





Eucampia zodiacus, Ehr., . 



,, gramlandica, CI., 

 Fragilaria striatula, Grev. , 



c 



r 



+ 



+ 



+ 







c 



+ 

















r 



















r 





Guinardia fiaccida, Per., . 



r 



r 



r 





r 



r 



r 





r 



Lauder ia annulata, CL, 











rr 











Leptocylindrus danicus, CI., 





r 



r 



r 



r 











Navicula membranacea, CI., 











r 











Rhizosolenia setigera, Brightw., . 



r 







rr 



+ 







+ 





,, Shrubsolii, 01. , 



Stoltcrfothii, Per., . 



+ 



r 



+ 



+ 



+ 



+ 



+ 



+ 



+ 





rr 



+ 





r 











pungens, CI., . 

 Roperia tessellata, Grun. , . 





+ 





+ 



r 





+ 



+ 













r 







r 





Skeletonema costatum, CI. , . 

















cc 





Stephanopyxis Turris, Ralfs., 



+ 



r 



+ 



r 



c 



c 



+ 



+ 



+ 



Thalassiosira Nordenskioldii, CI. , 



rr 









r 











,, gravida, CI., . 





rr 

















Thalassiothrix longissima, CI. et Grun., 



rr 



















These diatoms and their distribution were fairly typical of all the 

 localities, now one form, now another, varying in abundance ; but OJioeto- 

 ceros curvisetus, C. decipiens, C. didymus, Bhizosolenia Shrubsolii, Cos- 

 ci?wdiscus concinnus, Eucampia zodiacus, and Stephanopyxis Turris being 



