TERATOLOGY OF DIATOMS. 57 



are placed nearly at right angles, and the puncta follow the same direction 

 as the raphe. 



I have found other valves in the same collection, which are all 

 quite as peculiar and show that neither striation nor outline are invariable. 

 A few examples will bear out these remarks : 



Navicula lyra affords us a series of monstrosities : the margin is 

 excised or the outline becomes sub-hexagonal ; the lyre is normal on one 

 side of the raphe and infiexed towards the latter on the other side ; 

 in another example it is undefined and indistinct ; on the two sides of 

 the raphe the striae are duplicated close to the central nodule ; in another 

 example there is a straight hyaline line, in addition to the lyre and 

 between it and the margin ; lastly, in a further example, quite close to 

 the central nodule there is a kind of round spurious nodule surrounded 

 by a short radiant striation. 



Navicula Johnsoniana shows on the valve, spaces without striae and 

 placed asymmetrically on the two sides of the raphe. 



In a Cocconeis scutellum the striation is regular on the lower portion 

 of the valve, while it is undefined and takes all kinds of directions on 

 the upper portion. 



In a Campylodiscus dypeus the valve is broadly excised on one side 

 and the costae follow the outline of the excision. This does not always 

 form a void space, the excision being filled up by a fine membrane 

 showing an indefinite punctuation. 



In a Pyrgodiscus armalus all the large spines, with one exception, 

 are wanting. 



A Mastogloia rhombica shows a sinuous raphe. 



In a Triceraiiuvi Favus one of the margins is strongly concave, and 

 a hexagonal Triceratium dubium has its six sides very concave. In another 

 Triceratium dubium there are only five angles, one of which is more acute 

 than the others. 



An Auliscus punctatus has two false ocelli, while an Auliscus ccelatus 

 has three equal and well-developed ocelli. 



A Biddulphia pukhella displays a cuneiform frustule. 



In conclusion, for space does not permit me to enumerate all the 

 monstrosities in my possession, I will only mention further an Aulacodiscus 

 Comberi having only three appendices, an oval Eupodiscus radialus, and 

 an almost perfectly triangular Eupodiscus yonesianus. 



All these modifications of form, these monstrosities of excess and 

 defect will exemplify what has been above described. 



The Honourable Jacob D. Cox, of Cincinnati, has made a special 



