56 S. LOVEN, ON POURTALESIA, A GENUS OF ECHINOinEA. 



Pl. VIII, 73; very iiainute in Moira, ventral, Pl. X, 110; muricate, but rarely areolar, 

 ill Spataiigus purpui-eus, III, 109; Meorna, III, Pl. Vill, 70; Breynia, III, Pl. XI, 131; 

 Brissopsis, ventral, B. IX, 83; Abatus, III, Pl. X, 91; Ecliinocardium, III, Pi. Xi, 725, 

 128. All through the length of the tube they are generally of the same shape, but near 

 the top they regularly all at once assurae peculiar shapes, and combine in forming 

 the foot-ring, annidus, psellion, under the terminal part. In some the elements of 

 this ring are siniply enlarged modifications of those of the shaft, presenting an annular 

 complication of lengthened, arched, overlapping spicules, sometimes prickly, Brissus, 

 Pl. VIII, fig. 74, sometimes outwardly almost smooth, inwardly spinous and emitting, 

 at regular distances, strong spikes, Brissopsis Pl. IX, 85, or connected with centripetal 

 spökes, as in Brissus, Pl. Vill., 75, or in the phyllodean pedicels of Maretia, 64, 78, 

 which are composed of series of irregular flakes. In others the ring consists of areolar 

 prickly laiuels, small in Spatangus, III, Pl. X, 109, in Lovenia, III, 107, 108, larger, 

 subtriangular, as in Echinocardium flavescens, III, Pl. XI, 128, phyllode, 130. In others 

 again, as in the subanals af Lovenia, Pl. Vill, 76, Abatus, 77, in the frontals of Breynia, 

 XI, 131, and in Rhyuchopygus, XI, 119, the ring is formed by a single series of de- 

 tached, irregularly rounded, areolar scales. Echinocardium cordatum in this regard 

 deviates in a most extraordinary manner, not only from its congener E. flavescens, 

 but from all the rest of Spatangidaa. The tubes of the phyllodean pedicels are devoid 

 of spicules, and the ring is represented by a few small sigmoidal ones only; in the 

 shafts of the subanals there is a single row of similar spicules, most of them rather 

 broad in the middle and areolar, and the tubes of the pedicels of the III, within the 

 fasciola, present two rows of similar small and slender, slightly muricate spicules. In 

 the subanals, as well as in the frontals, there is no trace of a true ring, but close under 

 the top one single spicule, or in some cases two spicules, suddenly become of an enor- 

 mous size, Pl. XI, fig. 120, 123, lying across the tube, and even exceeding with their 

 pointed ends the diameter of the crown of filaments, and sometimes simple, sometimes 

 expanded in the middle, areolar and spinous, fig. 122, 124, 125. These gigantic spi- 

 cules, larger generally in the frontal pedicels than in the subanal, are seen as well in 

 the common European Echinocardium cordatum Penn. as in that called E. australe 

 Gray. It is difficult to conceive their probable use, unless they may be some sort of 

 stinging apparatus, a weapon added to the tactual and prehensile parts of the pedicel. 



The diversities in form and in function exhibited by the pedicels are represented 

 more or less distinctly by corresponding modifications of those special parts of the 

 skeletal framework which surround the canals, by which they communicate with the 

 ambulacral system in the interiör. These parts were called cancelli by older authors; 

 I shall venture to propose for them the appellation of peripodia. 



It was, no doubt, a bright thought of J. A. Gyllenhahl, in those days, now 

 more than a hundred years ago, to assimilate the »cancelli» of the »crj^stal äpples» to 

 those of recent Echini, and on that account to transfer their bearers to the animal 

 kingdom, ranging them under the great natural genus Echinus, then recently instituted 

 by Linn^us. And so close is in reality, on either side, the general conformity in structure 



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