43G ANIMAL NATURE OF DIATOMEiE. 



the figure given by Kiitzing, magnified as usual, 420 

 diameters, which, being 13 millim. long, corresponds to 

 0-0309. But the dimensions given in the definition (,5 = 

 0'564 millim.), are much greater. 



Monnema subinconspicimm, Mgh. 



I found it at Trieste, parasitic upon Ectocarjms arctus, 

 along with other Diatomese. 



The threads, oy filaments, are scarcely a millimetre long, 

 and are 0"085 broad. The Naviculse are 002 long, and 

 0'005 broad, as well on the primary surfaces as on the 

 secondary. 



The simplicity of the filaments had led me to believe 

 that the species corresponded to Naumena simplex of 

 Ehrenberg, excluding the synonym of S. temie of Agardh. 

 But the dimensions stated in the description {-^ — ^ijth of 

 aline, or 0'0052 — 0'0104 millim.), and the paucity of the 

 Naviculae included in the gigantic figure, seem to con- 

 ti'adict that association. 



Among the species ascribed by Harvey to the genus 

 Monnema (regarded by him as a simple sub-genus), the 

 four following are unknown to me ; spadiceum, Grev. ; 

 virescens, Harv.; diibium, Harv.; crinoideum, Harv. Three 

 others {implicatum, parasiticum, comoides), belong to the 

 subsequent genus. The last {p rostral urn) is an Encyonema. 



Of the remaining species described by Kiitzing as 

 Schizonema, and, therefore, wanting in partial tubes, I 

 infer from direct observation of authentic specimens, that 

 some belong to the following genus; araneosuni; trichoce- 

 phalum; Smithii; helmintJiosum ; scoparium ; sirospermum. 

 Of others T believe the same, from the figures of Kiitzing, 

 which disclose either partial tubes or so regular a hnear 

 arrangement of Naviculse as is never met with in Monnemce; 

 minutum, hnnile, floccosum, crispiim, plumosum, capi- 

 tatum, Bryopsis, Arhiiscula, hydruroides, mncosum. But 

 the two species lutescens and striolatum, which I do not 

 possess, appear to be true Monnenice. 



Finally, with respect to Schizonema illyricum, in which 



