KITTONj ON DIATOMACE.E. 17 



Pinnularia pereyrina. — Whilst examining the valves of 

 this form Avith a high power (800 diameters), I accidentally 

 discovered that the costoe are transversely striate on their 

 internal surface. The stria? are about 50 in -001 of an 

 inch. I have not been able to detect this peculiarity in 

 any other species, nor has it been noticed in any work with 

 which I am acquainted. Dr. Gregory, in ' Mic. Journ.,' Vol. 

 Ill, Trans., p. 15, says, " I may mention that a friend informs 

 me that the stria? on P. gracilis have been found by him to 

 be moniliform, although the fact may not yet be thoroughly 

 established. This, it ivill be observed, corj'esponds ivith Mr. 

 Smith's observation on the slrice of P. peregrinaP But where 

 does Smith say so ? 



I may mention that oblique light at right angles to the 

 valve is necessary to bring out the striae. 



VOL. VIII.— NEW SER. 



