450 ANIMAL NATURE OF DIATOMEyE. 



from Ralfs, and that he had named them as above. To 

 him, therefore, I leave the description. Length of 

 Naviculse 0'0337 millim.; breadth of the elliptico-elongate 

 secondary surfaces as much as 0'007 ; that of exactly 

 linear primary surfaces O'Ol. In this species I clearly 

 saw the so-called internal spermatia, in form at first 

 ellipsoidal, afterwards globose, varying in diameter from 

 0'028 to 0'05, furnished with a double envelope, within 

 which the internal granules grew gradually in size. 

 Similar in external appearance to Kiitzing's figure of the 

 following species. 



Schizonema hehnintosum, Chauv. 



The specimen with which I was favoured by Berkeley 

 corresponds perfectly with the figure and description of 

 this species given by Kiitzing, varying a little in the 

 assigned dimensions of the Naviculse. Length 0'052 

 millim., (Kiitzing says ^thof a line = 0*54 ; he figures it 

 1-1 2"'= 0-26 millim.,) breadth of the elliptico-truncate 

 primary surfaces as much as O'OOS, and of the elliptico- 

 rotundate secondary 0'012 ; less, therefore, than one third 

 of the length, which is the proportion indicated by Kiitzing. 

 In this species I have never been able to see the central 

 perforation with distinctness. As to the delicately crisped 

 fibres, described and figured by this author, I have 

 assured myself that they are nothing more than the 

 margins of thick partial tubes. 



Under the same name of Sckizonema Jielmintosum, and 

 with the indication of Chauvin (Alg. de la Norm., Fasc. IV, 

 No. 77), I received from Lenormand a Schizonema from 

 Calvados which differs very much from the preceding in 

 the dimension of the Naviculae, though very similar to it 

 in external appearance and in the forms of the Naviculae. 

 These are 0'32 long, and 0*007 broad. As in other 

 species, there are mixed among the larger Naviculae, 

 others smaller, some very small. Hence we may suspect 

 that the English species do not exactly correspond with 



