500 DR F. A. BATHER. 



(§ 520), and P. foriolus (§ 535). A key to the species (§ 551) is followed by a com- 

 parison of the British with the American species (§ 553). 



IV. Morphology and Bionomics. 



§ 578. I place these two subjects under one head because any separation of them 

 would involve considerable repetition. Or, quite simply, because I do not think 

 they ought to be separated. The attempt to discuss fossils, or for the matter of that, 

 recent organisms, as anything but living beings is foredoomed to sterility, or to fruitful- 

 ness only of error. Since, however, the essential quality of a living being is response 

 to environment, any discussion that omits the action and reaction between the outer 

 world and the structure of the individual may be good anatomy on the one hand or 

 good natural history on the other, but falls short of even an attempted morphology. 



§ 579. In the forms before us, forms by no means intimately related but falling 

 into two distinct Orders, the most obvious feature is a modification to accord with a 

 similar mode of life. And it is important to recognise that this is only a modification 

 — a change imposed by some outer necessity of the present on diverse anatomies 

 inherited from distinct pasts ; for the resemblances produced are so great, that 

 similarly modified representatives of these two groups have ere now been placed in a. 

 single Family. Briefly expressed, the modification is a change, from the normal erect 

 habit of a typical Pelmatozoon, attached to the sea-fioor by its stem and spreading 

 out its ciliated grooves for the collection of food more or less equally on all sides, to 

 a partially eleutherozoic or free-moving habit and a prostrate attitude, accompanied 

 by a superinduced bilateral symmetry and a flattened form parallel with the sea-floor, 

 having the food-intake at one end of the body, and the vent at the opposite end, 



§ 580. It is not maintained that this modification was due merely to the conditions 

 in the Starfish Bed. That idea would be opposed to the evidence of the fossils 

 themselves, since in each Order the forms found represent an earlier and a later stage 

 of the modification : Dendrocystis and Cheirocrinus the earlier, Cothurnocystis and 

 Pleurocystis the later. But, apart from that, we know the ancestors, and sometimes 

 the very near relatives, of these forms in the previously deposited rocks of other 

 countries. The Starfish Bed to a large extent merely perpetuated conditions that had 

 existed elsewhere, and thus prolonged the reign of creatures already adapted to such 

 conditions. The modification is, however, not merely preserved ; it is, in most of the 

 cases, intensified. Those who believe in orthogenesis, bathmic force, or whatever other 

 name they may give to the evolutionary application of the first law of motion, will 

 consider this intensification as the natural consequence of later geological age. While 

 they may be quite right, they cannot obtain any proof from the facts of this case. It 

 seems clear that the littoral conditions of the Starfish Bed, as of the approximately con- 

 temporaneous sandstones in Tyrone and South Wales, were particularly well suited 

 to these eleutherozoic cystids, and that the sandy waters evoked further responsive 



