16 



SCIENCE 



[N. S. Vol. XXVI. No. 653 



which no reference is here made) are found 

 the longest and most remarkable spines occur- 

 ring in the whole class. The section on the 

 " Classification of Asteroidea " is thoroughly 

 unsatisfactory and it is particularly annoying 

 that an Englishman should show such a lack 

 of appreciation of Sladen's great work, which 

 despite its defects is certainly the most care- 

 fully reasoned and well-grounded classifica- 

 tion of starfishes yet published. One is 

 almost inclined to believe that MacBride has 

 never read Sladen's philosophical discussion of 

 the principles of classification in the Aste- 

 roidea. The present reviewer dissents em- 

 phatically from the principles proposed by 

 MacBride, that " the best method of classi- 

 fication is to take as our basis the different 

 methods in which the demands of the environ- 

 ment have been met," and that " the great 

 differentiating factor in their development 

 must have been the means they adopt to 

 shelter themselves from their enemies " ; — 

 " One of their chief dangers " " must be re- 

 garded as " " assaults by other animals, espe- 

 cially parasites, on their soft and delicate 

 skins." According to these principles, the 

 influence of environment is far more im- 

 portant than heredity, and classification should 

 be based, not on the deep-seated, slowly modi- 

 fied characters, but on superficial externals 

 which are easily modified by changes in the 

 manner of life. It is clear to any one famil- 

 iar with the great variety of form and ex- 

 ternal features exhibited by starfishes that 

 " the demands of the environment " have been 

 met in widely different ways by closely related 

 forms, while the converse of this may or may 

 not be true. Moreover, starfishes have com- 

 paratively few enemies, after their larval life 

 is past, and certainly are not especially liable 

 to parasites as MacBride assumes. The great 

 majority of species are found more or less ex- 

 posed on the bottom or, at the most, concealed 

 beneath rocks, and there is not the slightest 

 evidence that the danger from parasites has 

 played the least part in the evolution of the 

 group. In view of his principles, it is not 

 strange that MacBride adopts the classifica- 

 tion of Barrier, of which no previous English 

 or American writer has approved, and divides 



the Asteroidea into five orders, each of which 

 is taken up in turn with its constituent fami- 

 lies. The latter are, as a rule, treated very 

 briefly, but the more important are made the 

 subject of many interesting and well-written 

 notes. The chapter closes with a short ac- 

 count of the fossil Asteroidea. The follow- 

 ing three chapters deal with the Ophiurans, 

 Echini and Holothurians, respectively, each 

 class being treated in practically the same 

 way as are the Asteroids. The account of the 

 morphology of each class is well-written and 

 very clear, with few mistakes or important 

 omissions. It is to be regretted that the ter- 

 minology used in connection with the pedicel- 

 larise of the Echini is not that which is now 

 almost universally used by echinologists. 

 Much attention is given the physiological as- 

 pects of the structures discussed, and some un- 

 confirmed observations on habits and func- 

 tions, made by other workers, are accepted 

 apparently without question, even though 

 somewhat improbable. As the classification 

 of the Ophiurans is still very imperfectly 

 worked out, MacBride has done well in fol- 

 lowing Bell's arrangement, but it is remark- 

 able that the very peculiar genus AsiropMura, 

 described by Sladen, is nowhere mentioned, 

 although its obvious resemblance to an 

 Asteroid makes it of great importance in this 

 connection. The classification given for the 

 Echini is apparently original and has much to 

 commend it, particularly its simplicity and 

 the clear-cut groups. Unfortunately it omits 

 the fossil forms (which are, however, dis- 

 cussed in a separate section) and for this and 

 other reasons, it needs some modifications. 

 The classification of the Holothurians is also 

 original, very much so in fact, and it is safe 

 to say will not be adopted by any student of 

 the group, recognizing, as it does, six orders, 

 of which only one contains more than a single 

 family. MacBride gives little heed to either 

 the work or the judgment of Ludwig, the 

 nestor of Echinoderm morphology, and by his 

 use of " Aspidochirota " and his failure to 

 mention the Synallactinse, he reveals either 

 ignorance or lack of appreciation of recent 

 work on the Holothurians. The chapter on the 

 Pelmatozoa is, at least from a zoologist's point 



