38 THE GKNUS TRACHELOMONAS, 



T doubt whether this form is best arranged under 2V. bulla Stein. 

 The characteristics of the latter are all wanting, viz , the ovate 

 body, long neck, and smooth (or very slightly denticulate) mem- 

 brane. 7?'. bulla itself, indeed, is of very doubtful validity, and 

 were it not for the fact that its forms are generally smooth, it 

 would probably before this have been arranged as a tail-less 

 variant of Tr. caudata. Lemmermann's form goes best under 

 7>'. spinosa Stokes, infra; note that in both forms, and in these 

 two only, all the spines point backwards. 



T7\ oblo7iga var. truncata Leram., ibid., T. xi., f.7, 8; Reise n.d. 

 Pacific, p. 344, 1899. Lorica oblong, 12-13 /x long, 11 /x broad, 

 truncate in front, squarely rounded below, with a short straight 

 truncate neck, membrane smooth. 



Tr. acanthostoma Stokes, Infus. U. S., p. 89, no fig., 1888; Proc. 

 Amer. Phil. Soc, 1887. Lorica subspherical, brown, two or more 

 irregular rows of short conical spines round the orifice, no neck, 

 membrane punctate, length 36 /x. 



Tr. spinosa Stokes, Proc. Amer. Phil. Soc, 1890, p. 7 6, f.l4. 

 Lorica oval, l\ times as long as broad; ends equally and evenly 

 rounded; spines slightly recurved, pointing backwards, longest 

 posteriorly : neck short, smooth, truncate, slightly narrowed 

 above; length 42 /x. The recurved spines, pointing backwards, 

 are characteristic of this type; cf. Tr. bulla viir. regidarius Lemm., 

 supra. 



Tr. <eres Maskell, Trans. N. Zeal. Inst., 1887, T.l, f.7. Oblong- 

 oval, smooth, with a low broad ring-shaped neck; length 35 /x, 

 breadth about 20 /x. Very like Tr. lagenella Dangeard (non 

 Stein), I.e., p. 132, f.40E, but with a low broad neck. 



Tr. armata var. Steinii Lemm., see note on Tr. armata var. 

 glabra, supra. 



EXPLANATION OF PLATES L-V. 



All figures enlarged 1000 diams., unless otherwise specified. 

 Plate i. 

 Fig. 1. — Trachelomonas volvocina Ehr. 

 Fig. 2. ,, ,, vsiv. punctata, •n.v'AV. 



Fig, 3. ,, ,, var. granulosa, n.var. 



