74 THE ROYAL SOCIETY OF CANADA 



Rhizosolenia, Skeletonema , Asterionella, Bacteriastrum, Biddulphia, and 

 Thalassiosira — and it is interesting to notice that all of these, except- 

 ing Bacteriastrum, have been found in the waters of the Bay of Fundy 

 and Gulf of St. Lawrence. With these Coscinodiscus asteromphalus , 

 C. radiatus and C. eccentricus should be classed as of markedly Planktonic 

 character and exceedingly abundant, while Synedra undulata and 

 A'itschia longissoma, though less frequentl}^ met with, show in their 

 extravagantly elongated forms, a marked adaptation to flotation. 

 Whether any variation in the relative number of these genera at 

 different seasons of the year, such as have been found by Prof. 

 Herdman in the waters of the Irish Sea, is to be found here as well, 

 has not yet been determined, continuous observations with special 

 apparatus being necessary to determine this point. 



4. The relations of the Diatoms to each other and to other forms 

 of life. Apart from the fact that the Diatom flora of purely fresh waters 

 is markedly in contrast with that of the sea — such forms as Pinnu- 

 laria, Stauroneis the Epithemias, Eunotias, the Tabellarias, Himan- 

 tidium and Diatoma being characteristic of the one, while the discoid 

 forms, such as Coscinodiscus, Cyclotella, Actinoptychus, and Hyalodiscus, 

 together with Triceratium, Isthmia, Acnanthes, Grammatophora, &c., 

 and the various planktonic forms, such as Chœtoceros, are equally 

 characteristic of the other, there would appear to be a certain asso- 

 ciation of genera with each other. Thus, among salt water forms, 

 Acnanthes , Rhabdonema and Grammatophora are usually found together. 

 The Nitschias and Synedras are similarly usually associated in the same 

 localities, as are the Melosiras, Gomphonemis and Licmophoras. 



The fact that Diatoms consntute the food of various shell fish 

 is now well established, and Diatoms usually abound where there 

 are natural sets of clams and oysters. Hence it may be inferred that 

 the abundance of Diatoms in the harbour and along the shores of 

 eastern New Brunswick and Prince Edward Island may have some- 

 thing to do with the further fact that these same shores, as at Shediac 

 and Buctouche, and of the Island, at at Malpeque, are also famous 

 for the abundance and excellence of their oyster supply. Diatoms 

 were also found in considerable numbers at the Biological station at 

 St. Andrews in the stomachs of sea urchins, scallops and Ascidians, 

 as well as those of fishes, not less than fifteen genera having been ob- 

 tained from the stomachs of flounders. 



It may here be noted that, accompanying the Diatoms in salt 

 waters, especially in Plankton gatherings, one is almost sure to find 

 specimens of the Infusorian, Distephanus speculum, formerly known 

 as Dictyocha and regarded as being itself a Diatom, also such forms as 

 Amphorella and Tintinopsis, often in great num])ers. Copepods and 



