IIS MISS M. E. J. CHANDLER ON THE [vol. IxXlX, 



In order to illustrate the difficulty thus occasioned, the following 

 instance is given. In the Isle of Wight four different species 

 occur at three different horizons, namely : S. headonensis, sp. nov., 

 in the Lower Headon Beds; S. neglectus, sp. nov., in the Bernbridge 

 Series; S. acuticostatus, sp. nov., and another which has been 

 retained as S. ivebsteri (see below) in the Hamstead Beds. All 

 these four had, at one time or another, been referred to S. websteri, 

 which had thus become a group-name to indicate any Stratiotes 

 from the Isle of Wight. But the absence of the types, and 

 ignorance as to which of the green clays near Newport had yielded 

 those types, combined with the poorness of the figures and de- 

 scriptions, left as a matter of doubt which of the four species was 

 the original- S. ivebsteri of Brongniart. Clearly, therefore, it was 

 necessary to go back to the beginning, and to obtain types (where 

 possible) which could be carefully compared. These have been 

 obtained in every instance but that of S. websteri. But in 1901 

 Zinndorf (60) had described and figured carefully under this name 

 a Stratiotes from the Upper Middle Oligocene of the Mayence 

 Basin, and his species agreed in all respects with one of the English 

 forms from the Hamstead Beds. In order to keep an old name, 

 familiar in the past literature of the subject, this species of Zinndorf 

 has been retained as S. websteri Zinndorf (? Brongniart). 



III. Stratiotes aloides: Diagnosis oe Fruit and Seed. 



In order that the relationship of the fossils with S. aloides may 

 be appreciated, and the past changes in the genus understood, a 

 description is given of the living seed. 



Fruit. — Excellent accounts of the fruit are extant by Lubbock 

 (39) and Nehring (57) ; but, as the seed alone is preserved 

 in fossilization, the structure of the fruit is of no consequence 

 here. 



Seed. — From one to four occur in each locule, generally a few 

 are abortive and stunted. Each seed is anatropous, almost erect, 

 situated in the locule with its raphe towards the centre of the 

 fruit, while the nearly contiguous hilum and micropyle are directed 

 towards the outside wall. In shape bisymmetric, oblong, narrow 

 and bolster-like, slightly hooked at the base, and very slightly 

 flattened laterally; provided with a keel in the plane of symmetry 

 running down one side from the apex to the base, and continued 

 just round the base on to the opposite side ; the keel carries the 

 raphe. At the proximal end a small knob-like projection, the 

 ' collar', occurs ; it is penetrated by the micropyle, and its presence 

 determines the hooked form of the seed. The collar is separated 

 from the main body by an ill-defined constriction — the ' neck '. 

 (See text-figure 1, p. 119 & PI. V, fig. 23.) 



The testa consists of three layers : (i) An outer layer of 

 spirally thickened cells, which swell in water and become mucila- 

 ginous. This is generally destroyed wholly or in part during 



