432 ANIMAL NATURE OF DIATOME^. 



in relation to the Paris line, or still better, to the smaller 

 one of Vienna, whilst, on the other hand, the figure would 

 disagree less with the admeasurement interpreted by the 

 conventional value of 2 millim., although ^th of such a 

 line would be equal to '01 84 millim. 



Monnema tenue, Kiitz., (Schizonema.) 



As in the preceding species, I also find in the authentic 

 specimen of Kutzing, as well as in others which I have 

 examined, that the size of the Navicula? corresponds to 

 the measure described in the definition in the line of 

 Paris Cms = 0-027 millim.) whilst the figure given with an 

 amplification of 420 diameters is only 5 millim., and 

 therefore corresponds to 0-012 millim. 



In this species Kutzing observed the presence and 

 development of the spermatia. 



Kutzing observes that his S. tenue does not correspond 

 with the 8. tenue of Agardh, therefore he ought to have 

 changed the name. 



Except for the figure of Agardh there is reason to 

 suspect that it belongs to a true Schizonema, though 

 published together with Micromcgce, which combine 

 a coriaceous consistence with the essential character 

 of partial tubes (' Icon. Algar. Europ./ fasc. i, tab. 3.) 

 I find, on the other hand, that the Schizonema frequent 

 in the Lagunes of Venice, by me denominated 8. adri- 

 aticum, is referable to this species, and not to the pre- 

 ceding one, where Kutzing would place it, and I persist 

 in regarding it as corresponding to the definition and 

 description which Agardh gives of this his own species. 



Under the name of Schizonema comoides, to which it 

 certainly does not belong, I received from Lenormand a 

 beautiful species allied to the preceding, but in which 

 the Naviculae are constantly smaller, scarcely measuring 

 O'OIS millim. in length. In these, the so-called external 

 spermatia are very abundant. This is an important 

 species, 'because the Naviculae, being very stipitate, and 



