The Miceoscope. 67 



Since this was written, Dr. W. J. Gascoyne has found one which 

 has the meridian line more prominent, the markings more distinct, 

 and only about one-half the size of the first one. While trying to 

 find a duplicate to these, I found some ten valves, nearly all badly 

 broken, and which, although they had the distinct feature of this new 

 genus in having the disk form and navicula center, yet were want- 

 ing in not having the beautiful marginal rim of the first one dis- 

 covered, but have a plain, distinct row of cells, which curve over the 

 edge, like the disk of a time coscinodiscus, so much so that it is almost 

 impossible to get a perfect photo with the high powers required to 

 bring out the markings. Not a single person to whom I have vn.*it- 

 ten and sent photos but has said it must be a double diatom, and 

 the only answer I can give is, how could the broken valves be two 



R. Febigerii. R. Febigerii. 



diatoms and yet broken perfectly across both, and this in some 

 ten specimens I have picked and mounted; neither can the high- 

 est powers or best objectives separate them, as the markings extend 

 in an unbroken line from center to circumference. One con'espond- 

 ent who has made the diatoms a study for many years, wrote: " This 

 truly can be called the missing link in the structure of diatoms, a 

 disk form with navicula center, meridian line and nodules. This 

 upsets (or confirms, as another high authority wrote) all former theo - 

 ries." I now have three species, and I will leave their placing to 

 those who have made a study of the life histoiy of diatoms. Prof. 

 H. Xi. Smith kindly gave them a name for me, Raphidodiscus, that 

 is, a disk with a cleft or raph, and I have called the first one found 

 Raphidodiscus Marylandica, n. g., the one without the rim, Ra- 

 phidodiscus Febigerii, n.g., and Dr. W. J. Gascoyne has named the 

 one found by him Raphidodiscus Christianii, n. g. I also sent 

 Prof. Smith photos of a square diatom, of which he has written: " I 

 am not sure that I have ever seen this diatom. Its outline is 

 familiar, but the oval interior I cannot recall, neither can I find that 

 it is figured. So far as I know it is new, and I would suggest the 



