Protococcacece 



223 



apices of the former, and I do not regard this as a sufficient 

 generic difference. " Reinschiella ? setigera " must be considered 

 as an Ankistrodesmus having the same relationship to other 

 species of the genus as Dactylococcus bicaudatus has to other 

 species of Dactylococcus. 



ou-ts 



Fig. 94. A, Ankjj&Mdtisin.Hx falcatu* (Corda) Ealfs, from Bowness, Westmoreland. 

 B and C, A. falcatus var. acicularis (A. Br.) ; B, from Pilrnoor, N. Yorks.; 

 C, from the plankton of Loch M. Bharabhais, Lewis, Outer Hebrides. D, A. 

 falcatus var. tumidus nob., from Puttenhaui Common, Surrey. E, A. falcatus 

 var. mirabilix nob., from Wimbledon Common, Surrey. F, A. setigerus (Schrb'd.) 

 nob., from near Bievanlx Abbey, N. Yorks. G and H, A. Pfitzeri (Schrod.) nob., 

 from the plankton of Loch M. Bharabhais, Lewis. (All x 520.) uuts, autospores. 



As plants of this genus are often very abundant and the synonymy is 

 much confused, the following synopsis will be found useful : 



A. falcatus (Corda) Ralfs. \Micrasteriasfalcata Corda 1835; Ankistro- 

 desmus fu-siformis Corda 1838 (in part); Rhaphidium fasciculatum Kiitz. 

 1845 ; Rh. polymorphism Fresen. var. falcatum Rabenh.] Cells lunate or 

 arcuate, 16 24 times longer than the diameter (1'5 3 /x), with the apices 

 acute ; associated in loose aggregates or close bundles, rarely solitary. 

 Chloroplast visually devoid of a pyrenoid. Fig. 94 A. 



Var. acicularis . \_lihaphidium aciculare A. Br. 1849 ; Rh. polymorphum 

 var. K<'t'rntre Rabenh.; Closterium subtile Breb. ; AnJri&trodesmus acutissim.ua 

 Arch. 18(5] Cells usually solitary, commonly straight or slightly curved, 

 with acutely attenuated apices. Length 36 65 /x ; breadth 2-5 3'5 /x. 

 Chloroplast sometimes furnished with one pyrenoid (or more). Fig. 94 B 

 and C. It is most probable that Eh. pyrur/i'iium ( 'hod. belongs here. 



Var. duplex . \_Rltphi<1itini <////i/e.r Kiitz. 1845.] Cells elongate, sig- 

 moid, associated end to end in pairs, lilt, inrale Chod. may possibly be a 

 form of this variety. 



