1894.] MICROSCOPICAL JOURNAL. 75 



at extremities, length 0.14: mm., width .Oil mm., median 

 line straight, curved at extremities, longitudinal striae 30, 

 transverse 27 in 0.01 mm. Habitat, salt waters, Connec- 

 ticut." 



The Connecticut form is about three times the length 

 of " eximiiim " as given in Brit. Diatoms, and has liner 

 stride ; and as it does not grow in tubes but is a free 

 traveller, I have always thought since my first discovery 

 of it more than three years ago that it required a special 

 name ; but the propriety of calling it " Gyrosignia " may 

 be questioned. 



Prof. Cleve proposes to divide the genus Plenrosigma 

 into two, retaining this name for those with oblique stria?, 

 and adopting Gyrosignia for those with straight. This 

 name was given by Hassell, and was rejected by Prof. 

 Smith, on account of the " alliterative blunder," De Bre- 

 bisson also comments upon it with disfavor. 



Plate III also shows in Figure 5, " Namcala theta, CI. 

 n. sp." which he credits to Oregon ; fresh water fossil. 

 This form is also very abundant in the Quinnipiac fossil 

 material, with many other related varieties, some of 

 which were rather doubtfully referred to NavicuLa pa- 

 silla, by Prof. Kain to whom I sent a slide. I think that 

 several of these varieties are yet undescribed any fur- 

 ther then in general terms in my former article ; they 

 were not included in the material I sent to Europe which 

 came from Davis' pit ; these varieties were in material 

 from Share's pit, about two miles farther North. Three 

 of these related varieties are very numerous in this ma- 

 terial ; they vary greatly in size and considerably in out- 

 line and also in fineness of striation,"the larger variety is 

 proportionally more elongated than the others and has 

 finer and less distinctly marked stria'. Cleve's figure is 

 an accurate representation of one of the smaller of these 

 forms, excepting that it does not show the stria? so dis- 

 tinctly moniliforn; ; the larger is more then three times 



