278 BihUograpliical Notices. 



with the final revision of the generic descriptions in one of the 

 three primary groups into which the Palteocrinoids are divided by 

 the American authors. This portion of the work appears to us to 

 be much tho most satisfactory one. In the extent and accuracy of 

 his personal acquaintance with the wonderfully complex generic 

 types which are presented by the Palaeocrinoidea Mr. Wachsmuth 

 has no equal, we had almost said no second ; and the immense 

 mass of detailed information which he possesses concerning the 

 intricate composition of calyx and vault in the Actinocrinidte, 

 Platycrinidae, and Rhodocrinidse is clearly and explicitly set forth 

 in Parts I. and II. and in this first section of Part III, of the ' He- 

 vision.' The order Palseocrinoidea is divided by himself and Mr. 

 Springer into three suborders, the first of which includes the three 

 families just mentioned and all other Paloeocrinoidea " in which the 

 plates of the test ai"e solidly united by suture, and in which the 

 lower arm-plates are incorporated by means of interradial plates so 

 as to form a part of the calyx." For this group the name Camarata 

 is proposed, while the Articulata (the Ichthyocrinidse of Part I.) 

 include " those families in which the plates of the test are united 

 by loose ligaments or muscles, and in which they are somewhat 

 movable." Lastly the group Inadunata (corresponding on the whole 

 to the Cyathocrinidoe of Part I.) " is proposed for all Paloeocrinoidea 

 in which the arms are free above the first radials and which have five 

 single interradials, located ventrally," The authors state that 

 " these groups are not only well defined in nature, as shown by the 

 fact that they are so readily recognized, but they are also most 

 convenient for all descriptive and comparative work." In this 

 remark we entirely concur, and wc fully believe that the classifica- 

 tion which the authors propose will stand the test of future research. 

 It has grown up gradually during the many years of Mr. Wachs- 

 muth's experience as a collector, and we doubt if any palseontologist 

 will be able to improve upon it. 



The view which the authors take of the Crinoids with regard to 

 the other Echinoderms appears to us, however, to be a less satis- 

 factory one. They follow the writer in adopting Leuckart's sepa- 

 ration of the stalked Echinoderms under the name of Pelmatozoa, 

 but only rank this group as a class equivalent to Urchins and Star- 

 fishes. The spirit of Leuckart's classification is thus entirely 

 ignored, though it is partially followed in the letter, and we are 

 taken back in principle to the grouping of the older systematists, 

 in which Crinoids, Cystids, and Blastoids were all thrown together 

 under the term Crinoidea, regardless of the fact that Miller's very 

 explicit definition of this term implies the presence of articulated 

 arms upon the radials, and that these appendages are absent in both 

 Blastoids and Cystids. 



Leuckart's separation of the Pelmatozoa from Urchins and Stel- 

 lerids on the one hand, and from Holothurians on the other, has 

 been abundantly justified by tho physiological and morphological 

 researches of the last twenty years ; and the difference of a Crinoid 

 from an Urchin or Starfish is far greater than their difference from 

 one another, as was long ago pointed out by Professor Huxley. 



