Maps illustrating the Distribution of Plants. 1 7 



Planaria subauriculata is a marine species, and was found 

 on a leaf of a young specimen of Laminaria saccharina grow- 

 ing near the lowest tide-mark. Kept in sea water, it seemed 

 to sicken sooner than most of its tribe, living with me little 

 better than two days ; and although the water had not been 

 changed, yet the coolness of the weather had preserved it from 

 putridity. Its motion was, in general, very rapid ; and so 

 smooth, continuous, and even, and made without the slightest 

 apparent effort, that it reminded one of the noiseless lapse of 

 time: but occasionally the worm would behave itself very 

 unseemly, rolling itself up until head and tail met; then un- 

 bending, and tossing up and down the tail, as if annoyed by 

 some pest of which it wished thus to rid itself. 



It is a genuine species of Planaria; but I have not been 

 able to identify it with any hitherto described. It certainly 

 approaches very nearly to the Planaria flexilis of Mr. Dalyell 

 (Obs. on Planaria, p. 5. fig. 1, 2.); yet there are differences, 

 which persuade me they are distinct, especially the transparent 

 circular spots in the neighbourhood of the eyes, of which 

 there is no trace in P. flexilis. I propose to distinguish them 

 by the following characters : — 



1. P. flexilis, body lanceolate, very thin, semicircular in 

 front, of a dull whitish or pale ash colour; eyes numerous, 

 in two clusters ; the intervening space like the rest of the 

 body. 



2. P. subauriculata, body lanceolate, very thin, obtuse in 

 front, of a yellowish-brown colour ; eyes numerous, in two 

 clusters, with a clear circular spot to each, and a clear in- 

 tervening space. 



Art. V. Observations on the Construction of Maps for illustrating 

 the Distribution of Plants, ivith Reference to the Communication 

 of Mr. Hinds on the same Subject. (Vol. VIII. p. 498.) By 

 Hewett C. Watson, Esq., F.L.S. 



After wailing a couple of months to ascertain whether any 

 other person would pursue the subject started by Mr. Hinds, 

 I take the liberty of offering some comments in reference to 

 the remarks of that gentleman and, on the subject generally. 

 Mr. Hinds writes, " As the subject of geographical botany 

 has as yet met with but little attention, it is not to be expected 

 that any maps with which we may be furnished would convey 

 much information. The few that exist are, therefore, very 

 bare of facts, containing merely the names of some plants, ac- 



Vol. IX. — No. 57. ' c 



