478 Reviews — R. Fourtau — Egyptian Echinoderms. 



Echinoids, M. Fourtau seems to be appalled by the great number of 

 species that are accumulating under certain generic names, and he 

 attempts to mitigate the evil by degrading certain ' species ' to the 

 ranks of varieties, races, and mutations. Tliis method seems fully 

 justifiable, so long as it is carried oiit uniformly. Unfortunately 

 M. Fourtau does not give any indication of the precise significance 

 (for him) of the three subspecific terms employed. It is possible, 

 from a study of the actual cases, to glean some information on this 

 score, but a simple statement, or a definition, would have rendered 

 the process of ' despecification ' more intelligible. It seems that, for 

 M. Fourtau, a ' variety ' is a form that diifers from the type in some 

 slight respects, but may be discovered over wide areas, including the 

 type locality ; while a ' race ' is a local variant confined to some 

 region other than the type locality. There is not sufficient evidence 

 to speculate on the propriety or otherwise of the use of the much 

 harassed term ' mutation '. 



An interesting feature of the variation of some of the species of 

 Hemiaster is the parallelism of the lines along which they tend to 

 vary. Tims the four different forms of H. cubicus are matched 

 closely by a corresponding four in JI. heherti. Here surely is 

 further evidence in support of the principle of the fixity of the trend 

 of evolution among separate but homogenetic races — a principle that 

 has been urged by the present writer in several recent papers. 



There is little of outstanding interest in the new species described 

 in the Catalogue, if we except the Schizaster. A fresh bridge has 

 thus been thrown across the Cretaceo-Eocene gulf by the occurrence 

 of so essentially Tertiary a genus in the Maestrichtien. 



One further aspect of the work demands comment. In the 

 Introduction M. Fourtau refers to a suggestion (made in the review 

 of the previous volume) that he should not confine his efforts to mere 

 description, but give to the world the ideas that his acquaintance 

 with these numerous Echinoids has surely engendered. He contends 

 that a catalogue is not adapted for the expression of personal opinions 

 on the material dealt with. Granted, but there are other channels 

 of publication. M. Fourtau also seems to infer that, until all the 

 material is known and systematized, conjecture and theory are alike 

 premature. Surely here he resigns himself to perpetual silence ; 

 there will be fresh material appearing throughout his lifetime, long 

 as we hope that period maybe. Indeed, such a suggestion, whether 

 it is prompted by tenderness of conscience or feebleness of courage, is 

 in every way to be condemned. The average human mind is not 

 a mere machine for the production and arrangement of species and 

 genera after the manner of a cash-register. These must be strung 

 together into a chain of evolution, even if some of the links have to 

 be imagined. The spurious links may be faulty, and require frequent 

 renewal or replacement, but, when some of the links are in their 

 right order, the rest can in time be adjusted. To change the simile, 

 M. Fourtau spreads before us many of the wheels, screws, and 

 springs of an intricate machine, all loose and in disorder. He, more 

 than any man, is capable of judging as to which cogs fit and which 

 portions are lost. Every year adds to the pile of fragments, and 



