ECHINOIDEA. I. 



109 



certainty, I think, can never be obtained, and there is nothing to be done but to resolve that the 

 species of de Loriol shall in future be taken to be the Psammechinus vcrruculatus of Liitken. 



To the description by de Loriol I shall here make some additions. A primary tubercle is 

 found on every ambulacral plate. De Loriol states that two ocular plates reach to the periproct; in 

 the specimen before me this is only the case with one plate. The genital pores are especially large. 

 The buccal membrane contains numerous small fenestrated plates both inside and outside of the buccal 

 plates; those outside the buccal plates are a little larger, a few are thick and carry pedicellarise, while 

 most of them are simple fenestrated plates, quite imbedded in the skin; a few bihamate spicules are 

 also found in the buccal membrane. The gills contain the usual fenestrated plates. The mouth-slits, 

 as observed by de Loriol, are small, but very distinct. The globiferous pedicellarise are very different 

 from those of the genera Echinus, Stcrcchmus, and Parechinus; by this reason only this species was 

 to be separated from those genera. The blade is quite closed to a thin tube without lateral teeth, as 

 in Spharechinus granularis; no neck; I suppose that glands are found on the stalk, but this fact could 

 not with certainty be substantiated from the dried specimen in hand. The tridentate pedicellarise 

 (PI. XXI. Fig. 2) have a broad, deep blade with a slight indication of a net of meshes in the bottom; 

 the valves join for almost their whole length, the edge is rather strongly, but simply serrate. The 

 ophicephalous and triphyllous pedicellarise of the common form. The spicules are very peculiar 

 (PI. XXI. Fig. 28), small, with a little ball at each end, quite resembling dumb-bells. They are found 

 in especially great numbers in the globiferous pedicellarise, also, however, in the tube feet, but in 

 rather small number. Genuine bihamate spicules do not appear to be found in the tube feet. 



This peculiar form of globiferous pedicellarise and spicules is also found in « Echinus Robil- 

 lardz, and darnbeyensis^ further in the genera Toxopncustes and Tripneustes, and there can be no doubt 

 that the mentioned species belong here. To which genus they will have to be referred cannot be 

 decided, until we have examined the Toxopncustes- and Tripucustes-species. 



Echinus Robillardi Loriol. To the description of this species by de Loriol (245 p. 23) I may 

 add the following informations (a specimen received from Prof, de Loriol). A primary tubercle is 

 found on every ambulacral plate. The peristome is very peculiar, quite naked. Inside of the buccal 

 plates a belt is found with numerous bihamate spicules, and in the inner edge a few larger, irregular 

 needles are found (PI. XXI. Fig. 24. b). At the outer edge of the peristome again rather numerous 

 bihamate spicules are found, and in the gills seem to be found, not the usual fenestrated plates, but 

 numerous bihamate spicules. Otherwise no other plates than the buccal ones are found in the buccal 

 membrane; these buccal plates are not placed in pairs opposite to each other as usual, but one out- 

 side the other; neither spines nor pedicellarise are found on the buccal plates. The very peculiar, 

 oblique apical area has been accurately described by de Loriol, who also points out that the slits of 

 the test are small and indistinct. The globiferous pedicellarise as in Sphat echinus , without lateral 

 teeth, the blade a closed tube; I have not been able to decide from the dried specimen in hand whether 

 glands are found on the stalk. The tridentate pedicellarise very peculiar (PL XXI. Figs. 4, n); the 

 lower part of the blade is narrow and quite filled by a net of meshes, so that the edges are quite 

 coalesced; the upper part is a little widened with straight, finely serrate edge. Only this part of the 

 valves join, so that they are wide apart below. The ophicephalous pedicellarise without conspicuous 



