ECHINOIDEA. 1. nn 



rightly mentioued as a cliaracter of the Echinometrids that tlie globiferous pedicellariae .se termine(nt) 

 par deux crochets, mais ces deux crochets naissent a des liauteurs differentes, quoique assez rapproches 

 du sommet du Pedicellaire ». Even if Perrier has not understood this feature quite correctly, his 

 figures are sufficiently clear and good. Accordingly no excuse can be found for the later authors, 

 when they have overlooked this excellent character and in stead of it have stuck to the useless ones: 

 the number of the pores and the form of the test. If they had made use of this character, they might 

 have avoided the many systematical errors they have now fallen into. Beyond the peculiarit\- of the 

 globiferous pedicellariae of the Echinometrids empha.sized by Perrier, no attempts, as far as I know, 

 have been made to find other characters in the structure of the pedicellariae that might be used for a 

 limitation of larger or smaller groups inside this difficult division of the Echinids. The reason why 

 no such characters have hitherto been found, is partly that far too few genera and species have been 

 examined, partly that the examinations have not been made with sufficient exactness. My examina- 

 tions have shown that in the structure of the pedicellarice such peculiarities are found as yield excel- 

 lent characters, by wliich the genera mav be grouped. 



In i-~Echinus» miliaris and some other species the blade of the globiferous pedicellariae is 

 provided with a larger or smaller number of teeth on either side; the edge is not thickened, but thin 

 and sharp, and continues directly into the teeth ; there are no cross-beams connecting the edges across 

 the inside of the blade (PI. XVII. Figs, i, 7). In Echinus csciilentiis a. o. the edges are connected b\' 

 cross-beams across the inside of the blade; they may be few and narrow, or so strongly developed, 

 that the inside of the blade is almost quite covered with the exception of a series of larger or smaller 

 holes along the median line. One or more pairs of lateral teeth are found placed on the thickened 

 edge, but they do not form a direct continuation of it as in the preceding form (PL XVIII. Figs. 2, 3, 

 etc.). — In Echiiionietra and the forms allied to it, as alread\- mentioned, only one large lateral tooth 

 is found on one side (PI. XIX. Figs. 4, 13), and in Sfroi/gylocenfrotus, Sphcerechimis etc. no lateral teeth 

 are found at all (PI. XX. Figs. 14, 16, 26, etc.), only a little obliquity near the point shows that this 

 form must be regarded as a further development of the pedicellaria that is provided with one unpaired 

 lateral tooth, — not so much the strongly modified form in Echinometra as the less modified form in 

 •.^Ech.-> albocinctiis. Besides these differences in the structure of the valves, also a few peculiarities in 

 the structure of the stalk and in the neck are to be noted. In most genera the stalk consists of 

 numerous long calcareous threads connected with each other by a few cross-beams; in some forms, 

 Strongylocentroins drobachioisis and its nearest relations, it is a thin perforated tube. In most forms 

 the neck is quite short, or, more strictly speaking, quite wanting, in a few ones — also the Strong. 

 drobachic)isis-oxo\v^ — there is a long neck provided with powerful longitudinal and circular muscles 

 (PI. XX. Figs. 25, 29). 



The other pedicellariae seem only to contribute little to the limitation of the genera, still less 

 to the characterization of the larger groups; on the other hand the tridentate and ophicephalous pedi- 

 cellariae yield often excellent specific characters. The triphyllous pedicellariae are exceedingly similar, 

 and yield scarcely any sufficiently certain systematic character, with one exception: Evechinus chloro- 

 ticiis; in this latter some digitate prolongations pass from the upper end of the apophysis over the 

 blade (PL XIX. Fig. 29), a quite unique feature. As a common feature may be noted that the edge is 



The Ingoif-Expedition. IV. i. I^ 



