104 SPECIES OF DESMIDS. 



,, r . Angles in end view trifid trifiditm, 123 



g. " " " simple or bifid (ss). 



h. Arms trifid or bifid; end view 3-4 radiate; arms smooth, 



brachiatum, 124 

 h. " end view 3-radiate; arms aculeate, rough, 



aspinosvm, 143 



h, " end view 5-6 radiate . . . distent-urn ^ 149 



h. " end view 7-9 radiate .... Rot-ula, 135 



h. Arms truncate, oblique, geniculate, short; end view 4-radiate, 



inconspicu urn, 125 



//. Arms acute or aculeate, curved; end view 3-radiate . sudeticum* 

 i. Ends separated by a more or less elongated isthmus (/). 

 i. Ends approximate (z). 



j. End view fusiform, with a central obtuse inflation, leptocladum, 136 

 j. oval, a long arm on each side, 



grallatorium, 136; ungulatum^ 136 

 j. End view triangular or 3-radiate (k). 

 j, " quadrangular or 4-radiate (/). 



j. " 5 -radiate (v). 



j. " 6-radiate (). 



y. 7-8 radiate , Ophiura, 134 



/. Isthmus basally inflated; cuspidate or spinous (/). 



k. " not basally inflated; cuspidate not spinous (///). 



/. Isthmus basally inflated elongatvm, 130 



/. with a 1-4 cuspidate protuberance on each side; arms 



short fasciculoides, 130 



/. with i notched spine on each side . . . spinosum, 139 



;//. Diameter -g-i-g- in. (5o/<) or less (). 

 m - " ror m - ( 6o /0 or wider (o). 



n. End straightish, sides tapering into short, mostly obtuse processes, 



tricorne, 126 



n. End broadly convex; processes curved .... cyrtocerum, 128 

 n. " " processes straight, slender . . gracile, 133 



o. In end view the angles produced in long arms, 



vestitum, 138; pseudosebaldi, 139 



o. In end view the angles not produced in long arms,* Sebaldi, 138 

 /. Isthmus basally inflated or cuspidate (r). 

 p. Isthmus not basally inflated nor cuspidate (s). 

 r. Isthmus basally inflated, corrugated and denticulate, tetragonum, 130 

 r. with a short spine on each side . . . odontatum, 134 



*Journ. R. Micr. Soc., Dec., '85. 



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