ECHINOIDEA. I. 



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

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

 (ArcPosoHiaJ a singnlar kind of pedicellarice are found, the tetradactyle, with four peculiar, verv ele- 

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

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

 only a single genus ( TrouiikosoDia); on the other hand, triphyllous and tridentate pedicellariae 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 pedicellariae, 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 pedicellaria; of the Echinidse; but they are of a quite different structure, the gland 

 being here jDlaced inside the blade, quite surrounded b\- the calcareous skeleton, while in the Echinidse 

 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 ojjening ( 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 resjject. Perrier (op. cit.) gives these pedicellarise a special name 

 Pedicellaires armees». After the discovery of the above described form of globiferous pedicellariae 

 in the Echinothurids^) there seems to be sufficient reason to take these pedicellaria; in the Cidarids 

 to be homologous with the globiferous pedicellariae 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. inernies> for the tridentate pedicellariae of the 

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

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

 species of the tridactylons 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 pedicellariae, 

 it may in fact be imi^ossible 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 pedicellarise; in the 

 l^resent work they will the mentioned as tsmall globiferous pedicellariae:>. — Ophicephalous and triphyl- 

 lous pedicellaria; are not found in the Cidarids. 



O. F. Mil Her 3) has originally given names to the pedicellariae, 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 Echuius has used other appellations: 

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

 Sladen (366) justly maintains that it is incorrect to use these latter names. The figures of Mitller 



1) What has hitlierto been regarded as ophicephalous pedicellariae in the Echinothuridte, are in reaHty triphyllous ones. 

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

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

 3) Zoologia danica. 17S8. pag. 16. Tab. XVI. 



Tlie Ingolf-Expedition. IV. I. 2 



