268 



NATURE 



\yuLy 1 8, 1889 



crimis of Vanuxem, Atelecystis of Billings, Echiiiosphaera 

 of Wahlenberg, Lichenoides, Trochocystis, and Rhombifera 

 of Barrande, the latter formerly referred by him to the 

 Pteropoda ; and, lastly, the undefined Cystidea. which is 

 reserved for the reception of eight or nine doubtful forms, 

 some of which may, at a future date, form the types of 

 yet more genera. It should also be noted that one species 

 — Echinosphaerites infaustus, Barr. — has been taken by 

 Prof. Neumayr as the type of his genus Arachtiocystis. 

 The same authority refers the somewhat doubtful 

 Rhombifera mira to Stephanocrinus, and points out 

 that Staurosoma is the same as Tiaracrinus of Schultze. 

 The genera of this group have been peculiarly unfortunate 

 in the names attached to them. It is no longer necessary 

 for palaeontologists to cumber their generic names with the 

 termination ites. This peculiar corruption of \l6o<i seems 

 to set a stigma on fossils, as though they never had been 

 living beings after all. The neontologist is ready enough 

 to throw stones at the palaeontologist ; there is no need 

 for the latter to supply him with ammunition. Prof. Lovdn 

 dropped this affix when editing the Cystidea in Angelin's 

 " Iconographia Crinoideorum," and surely the names are 

 long enough without it. Of far more importance is the 

 correct use of the terminations cystis, cri?tus, blastiis, and 

 the like. We extend indulgence to certain old authors 

 who gave such names as Agelecrittus and Cryptocrinus to 

 cystids before the Cystidea were distinguished as a class ; 

 but when once the divisions were recognized, we must 

 suppose that the eminent palaeontologists who used these 

 terminations attached to them some meaning. Even in 

 1843 we find Messrs. Austin suggesting that the names 

 Sycocrinites, Austin, and Echinocrinus, Agassiz, "require 

 amendment, as their terminations imply affinities which 

 do not exist." Apiocystis means a pear-shaped Cysfid, 

 just as Apiocrinus means a pear-shaped Crinoid : the two 

 terminations are not interchangeable. Posterity, for whom 

 we labour, will lament that we had not the strength of 

 mind to correct such names whenever we saw them to 

 be misleading ; but we ourselves should surely blame 

 most severely those who still add to our perplexity. Why 

 for instance, should Prof, von Koenen give the names 

 Corylocriniis ^.nd. Juglandocritius to two genera which he 

 himself describes as Cystidea ? In no other branch of 

 science would such a use of language to conceal thought 

 be tolerated. The present work we are glad to find free 

 from such flagrant absurdities. The errors of nomen- 

 clature are slight : the name Atelecystis, Billings, the 

 validity of which was upheld by Dr. H. Woodward, is 

 though not consistently, supplanted by its synonym 

 Anojnalocystis ; there is also a want of consistency in 

 writing Pyrocystites p'witm. No attempt, however, has 

 been made to revise the nomenclature of cystids foreign 

 to Bohemia, in which direction much will some day have 

 to be done. 



Chapters iv. and v. are devoted to the geological and 

 geographical distribution of Cystidea in general and of 

 Bohemian cystids in particular. Chapter vi. describes 

 the variations seen in the Bohemian species. The seventh 

 and last chapter discusses the connection of these species 

 with those of other countries. These questions are worked 

 out, from a statistical if not from a philosophical point of 

 view, in a large series of tables ; a few graphic curve- 

 diagrams would have been a more helpful guide through 



the wilderness of figures. The numbers of the species 

 found in the various beds of Bohemia are : — 



This vertical distribution agrees in its main proportions 

 with that observed in almost all other countries. The 

 chief exceptions are the States of New York and Wis- 

 consin, where a relatively large number of species are 

 found in the Niagara limestone, and England, where 

 seventeen species are recorded from Ordovician beds and 

 nine from the Wenlock limestone : none of the Wen- 

 lock genera occur in the corresponding beds of Bohemia. 

 The geographical diffusion of the Cystidea is very slight ; 

 the most widely distributed genera are Agelecrinus, 

 Atelecystis, and Echinosphaera. 



These elaborate comparisons and tabulations are, how- 

 ever, a little bit out of place in dealing with such a hetero- 

 geneous assemblage as the Cystidea. They are not a class, 

 but a collection of puzzles to which we relegate all echino- 

 derms that will go nowhere else. Barrande does indeed 

 attempt a definition (pp. 23-24), but not one character men- 

 tioned is common to all Cystidea. What one really looks 

 for in such a monograph as the present are new facts that 

 may throw light either on the connection between indi- 

 vidual genera and other classes of the Echinodermata, or 

 on the origin and meaning of the various peculiar organs. 

 Taking as guide the motto of Barrande, C'estce que faivu, 

 we shall enter into no speculations, but shall mention 

 such facts of morphological importance as appear to be 

 new. The state of preservation of the Bohemian Cystidea 

 is exceptionally bad ; but it would be hard indeed if so 

 rich an assemblage had not yielded to such an observer 

 some interesting results. 



Following the order adopted by Barrande in his second 

 chapter, we begin with the stem. The stem of the Pel- 

 matozoa typically consists of a single series of cylindrical 

 joints with a central perforation. In the earlier crinoids 

 the lumen is comparatively large ; in most stalked cystids 

 it is still larger. In Atelecystis, Mitrocystis, and Troclw- 

 cystis, the proximal part of the stem consists of a double 

 series of alternating plates which are thin and inclose a 

 large hollow. In Arachnocystis the whole stem consists 

 of four or five series of alternating plates. In Dendrocystis 

 the plates forming the upper part of the stem can only be 

 distinguished by their smaller size from those forming the 

 calyx ; below they merge into the normal series of single 

 joints. Cigara Diisli is the fanciful name given to a stem 

 entirely composed of small irregular plates, and probably 

 belonging to Lapillocystis fragilis. These facts forcib] 

 suggest that the Pelmatozoan stem originated as a m^ 

 evagination of the perisome. The curiously elong; 

 Pilocystis (PI. II. Fig. 26) may represent a still earli 

 stage in its evolution. 



The test of Cystidea has usually been regarded 

 composed of one simple layer of plates. Eichwald, 

 Lethcea Rossica, mentioned an epidermis, but seems 

 many cases to mean by this nothing more than i. 

 outer surface of the plates. Lovdn, in his monograph 

 Pourtalesia, seems to assume the existence of three ele- 

 ments or layers in the test. Barrande, however, has been 

 the first to conclusively demonstrate that in a number of 

 genera the main layer of the body-plates is closed, bot. 



II 



