426 Reviews — Wachsmuth 8^ Sprwger's Monograph on Crinoids. 



with certainty as a means of determining the true nature of an 

 apparently monocyclic crinoid. Neither space nor the subject in 

 hand permit the application of it on the present occasion to all 

 doubtful cases. I may, however, state that it leads me to regard 

 Bhizocrinus as pseudomonocylic, a conclusion to which Wachsmuth 

 and Springer have come on other grounds (p. 63). On the other 

 hand, they consider Bathycrinus and Hyocrirms as " true monocyclic 

 forms." Direct evidence is entirely wanting in the case o^ Hyocrinus ; 

 but as for Bathycrinus, the figures of the nerve-cords published by 

 P. H. Carpenter and D. C. Danielssen ^ lead me to place it among the 

 Dicyclica Inadunata. 



Hitherto scant attention has been paid by neontologists to the 

 orientation of the axial cords of the stem, and of the chambered 

 organ, and to the intimate structure of the capsule of the latter. 

 For example, the magnificently detailed and elaborately illustrated 

 account of Calamocrinus by that skilled anatomist of Echinoderma, 

 Mr. Alexander Agassiz, throws no light whatever on this essential 

 point. Perhaps it is not too late to hope that he may yet be able 

 to elucidate it fi-om his material. If those provided with the modern 

 means of microscopic research and with opportunity' to use them 

 have their attention turned to this inquiry by the present review of 

 Wachsmuth and Springer's important researches, it will have been 

 written to good purpose. 



Both basals and infrabasals are primitively five in number. But 

 the basals of monocyclic, and the infrabasals of dicyclic, crinoids 

 may become changed in number and shape by fusion and growth. 

 These changes and their relations to the anal plates of the cup are 

 fully discussed in the Monograph. There are also several statements 

 as to the position assumed by the smaller basal or infrabasal in those 

 cases where the base consists of one small and two large plates. 

 This latter is a point on which much stress has been laid, but 

 I believe its importance is exaggerated. It is, for instance, stated 

 by Wachsmuth and Springer that " in all Crinoids with an unequally 

 tripartite, monoc}'cliG base, the smaller plate is located to the left 

 of the anterior radial." This is not correct. In Storthing ocrinus 

 the small basal is the left posterior, as may be gathered from the 

 figures of Schultze ^ on pi. x (not on p. 69, which is wrong), and 

 from the recent description by D. and P. Oehlert,^ who discuss this 

 question under somewhat mistaken notions. In the " Crinoidea of 

 Gotland " specimens of GissoQriniis were described with the small 

 infrabasal in the left posterior and right anterior radii ; but 

 Wachsmuth and Springer have always found it in the anterior radius 

 in allied genera. It is hardly correct to state that " the anal plate 

 of ' Dicyclica ' rests invariably upon the truncated upper face 

 of the posterior basal " (p. 59). 



^ " Norske Nordhav's Expedition : Crinoida." 



^ " Echinodermen des Eilier Kalkes " : Denkschr. Ahad. Wiss. Wien, xxvi, 

 pp. 113-230, pis. i-xii; 1867. 



^ " Foss. DevoB. de Sta. Lucia" : Bull. Soc. Geol. France, xxiv, pp. 814-875, 

 pis. sxvi-xxviii ; 1897. 



