Page:Transactions NZ Institute Volume 15.djvu/336
clature this would be: length 274 μ; breadth, 240 μ. All my New Zealand specimens which I can consider as full grown have a length not less than 320 μ, and many range as high as 400 μ. The average difference is shown in the diagram, fig. 16d.
Secondly, I think the teeth of the lateral lobes are more numerous, and sharper, than those of the European plant, supposing that is that Ralfs' figure may be taken as the general form. My figure 16a shows the number and character of the teeth in a full-grown plant.
Thirdly, and this is probably an important character, the extremity of the end lobe shows divisions which I am not sure that I find in previous descriptions. As shown in fig. 16a, and more highly magnified in 16c, the extremity of the end lobe has the two teeth at the angles, but it is also deeply divided by a median elliptical cleft, and at the opening of this cleft, on each side, are two short spines or teeth, each pair converging so as almost to close the cleft; and the pairs are not on the same plane, the lower ones appearing as if from a mammillate inflation on the subdivision of the lobe.
Are these specific distinctions? I am not prepared to say. With regard to the last, Rabenhorst's phrase is—"lobo polari angusto cuneato prominulo, in apice plus minus profunde sinuato- vel undulato-exciso, angulis oblique truncatis vel bidentatis." Mr. Archer (in Pritchard, Inf. p. 727,) says, "End lobe very slightly exserted, its angles very slightly produced, bidentate, ends emarginate." Possibly neither phrase can be construed to include such a cleft as that shown in our plant. As for the spines, they might at first sight be taken for those of M. fimbriata, but they are less hairlike than in that plant, and besides there is never any sign whatever here of the spines seen on the teeth of M. fimbriata, in the lateral lobes.
In my figure 16b I represent a specimen which only once came under my notice, amongst perhaps a dozen of the ordinary form, and which I take to be a young state of the plant. It is smaller in size, but the cleft of the end lobe is there. The angles of that lobe are scarcely bidentate, and the spines at the cleft are inconspicuous. And the teeth of the lateral lobe are of irregular form, some truncate, some sharp. It appeared to me that the specimen was certainly immature.
On the whole, I hesitate yet as to the identification of this plant, and being unable to make up my mind on the point, leave it as M. rotata. In the character of the endochrome, in the arrangement of the amylaceous vesicles, and in the mode of self-division (as noted in my former paper) it resembles the European species. When a zygospore is found, the doubt may be cleared up, but we may have to wait some time for that.