ECHIXOIDEA. I. 



of which ends in a fine pore at the end. The rods reach only half-way, the whole thing is coalesced 

 to the very point; there are no muscles between the basal parts of the valves. In another genus 

 (ArtrosomaJ a singular kind of pedicellarise are found, the tetradactyle, with four peculiar, very ele- 

 gantly formed valves. Also in other Pvdiinoids a four-valved pedicellaria may now and then be found, 

 but only as an abnormity. Ophicephalous pedicellarise 1 ) are among the Echinothuridse found in 

 only a single genus (Tromikosoma); on the other hand, triphyllous and trideiitate pedicellarise are 

 found in all of them, and especially the tridentate ones show a great variety of forms, and are of great 

 systematic importance. In the Cidarids are found tridentate pedicellarise, and another kind occuring 

 in a large and a small form, of substantially the same structure. They seem to be poison-apparatus 

 as the globiferous pedicellarise of the Echinidae; but they are of a quite different structure, the gland 

 being here placed inside the blade, quite surrounded by the calcareous skeleton, while in the Echinidae 

 it is situated on the outside of the blade. On the inside of the blade, somewhat below the point, there 

 is a larger or smaller opening (the mouth ) in the calcareous skeleton, filled with large cells, richly 

 provided with cilia (sensitive hairs?). The efferent duct of the secretion of the gland passes up through 

 the end-tooth, and opens on its surface. How these structures are arranged in forms with no end-tooth 

 is unknown. The inner opening is of great systematic importance, while the glandular opening itself 

 scarcely is of any importance in this respect. Perrier (op. cit.) gives these pedicellarise a special name 

 Pedicellaires armeess. After the discovery of the above described form of globiferous pedicellarise 

 in the Echinothurids 2 ) there seems to be sufficient reason to take these pedicellarise in the Cidarids 

 to be homologous with the globiferous pedicellarise of the Echinoids, as has also been done by Stewart 

 (379) and Prouho (327), so that there is no cause to keep the name given to them by Perrier. 

 There is still less reason to keep the name Ped. inermes for the tridentate pedicellarise of the 

 Cidarids; there can be no doubt but that they correspond to the tridentate pedicellarise of the other 

 Echinoids (Pronho (327), Koehler (217)). Hamann (184) regards the small pedicellarise as a siib- 

 species of the tridactylous ones. Now it has to be admitted that sometimes it may be rather difficult 

 to distinguish between these latter and small tridentate pedicellarise; but generally they are very easily 

 recognised, and there is no doubt that, with regard to structure, they resemble very much the large 

 globiferous pedicellarise. Where no pronounced difference is found between large and small pedicellarise, 

 it may in fact be impossible to decide, whether a certain specimen is to be regarded as a large or as 

 a small form. There seems to be no reason to give a special name to the small pedicellarife; in the 

 present work they will the mentioned as small globiferous pedicellarise:*. Ophicephalous and triphyl- 

 lous pedicellarise are not found in the Cidarids. 



O. F. Miiller3) has originally given names to the pedicellarise, viz. Pedicellaria globifera, 

 triphylla, and tridens. These names have not been generally accepted, the reason being especially 

 that Valentin in his classical monograph on the anatomy of Echinus has used other appellations: 

 Pedicellaire gemmiforme, tridactyle, and ophicephale; these names have become the common ones. 

 SI ad en (366) justly maintains that it is incorrect to use these latter names. The figures of Miiller 



') What has hitherto been regarded as Ophicephalous pedicellariae in the Echinothuridse, are in reality triphyllous ones. 

 2 ) Also the globiferous pedicellariae in Stoinofiiiftistfs seeui to form a peculiar type. They have no end-tooth, and 

 there seems to be no poison gland on the outside of the blade. 



.i) Zoologia danica. 1788. pag. 16. Tab. XVI. 

 The Ingolf-Expedilion. IV. I. 2 



