ECHINOIDEA. I. 115 



than others, wlien it has first been pubhslied. I must decidedly follow Bell and de Loriol in the 

 opinion that the name of Tripnrustcs has the priorit}'. 



The species « Echinus > Robillardi^ darnleyensis, and verruculahts belonj^-, as stated above, also 

 here, but to which genus? They have, all of them, a primary tubercle on all the ambulacral plates; 

 by this feature they are excluded from the genera Toxopnnisfcs and Tripneiistes, this character being 

 here evidenth- of rather more value than among the Ec/ii/iiis-apecies. They must then either be 

 referred to Psaiinncchi)ius or form a new genus. In vrrriiciilattis the buccal membrane contains 

 numerous fenestrated plates, to be sure much smaller and finer than in varicgatus^ where the buccal 

 membrane is closely covered with large, thick plates; but in this respect scmittibcrculatus keeps an 

 intermediate position between the two, so that no definite limit can be given. The feature is quite 

 analogous with that of Parcchiiiits iiiicrofiibcrciihitiis^ miliaris, and angulosus. Otherwise I can see no 

 character that would justifv a referring of this species to another genus. The mouth-slits are in no way 

 smaller than in small specimens of varicgatus of a corresponding size; in a specimen of verruculatus 

 of a diameter of 21"" thcN- ha\-e a depth of i""", in a specimen of variegatiis of a diameter of 23™™ 

 they have onlv the same depth. Further the coloration of the test in young variegatiis is so ver>' 

 similar to that typical of vcrntciilatus, that a comparison gives the immediate impression that they 

 must be verj- closely allied. Accordingly I can only regard it as correct to refer this species to the 

 genus Psanniicchinus^ where it has already been referred by Liitken — who did not, to be sure, inter- 

 pret the genus Psammecliinus in the way it is done here, since he establishes the genus Psilechinus 

 for Ps. varicgatus^ and in the same paragraph he names verruculatus as a t\-pical Psammechinus^). 



The species Robillardi and darnlcycnsis are distinguished from Psaiiuuecliimts by their naked 

 buccal membrane; it is, as described above, quite naked with the excej^tiou of the buccal plates, but 

 contains more or fewer irregular spicules in the inner edge. The spicules of the pedicellarise are not 

 quite dumb-bell-shaped as in verruculatus and the other PsaiiiDiec/iinus-s^itci&s^ but are formed as 

 bows, which are a little thicker at the ends or of the same thickness in their whole length. These 

 two features, I think, render the referring to the genus Psai/iincchinus impossible, and they must con- 

 sequentl}' fonn a separate genus, for which I propose the name of Gymnechinus. 



Whether Toxopn. uniculatus realh- belongs to Toxopneustes or must rather be referred to 

 another genus cannot be decided from the existing descriptions. 



To the genus Evec/iiuus Verr. are referred the sjiecies chloroticus (Val.), australice Woods, and 

 raritubcrculatus Bell; of these I have examined cliloroticus and rarituberculafus (the type specimen), 

 with regard to which I can give the following informations in addition to what is hitherto known. 



Evechinus cliloroticus (Val). The 4 — 5 nethermost ambulacral plates have all a primar\- 

 tubercle, then only every other plate, and above the ambitus only every third plate has a primar>- 

 tubercle. In small specimens a primary tubercle will thus be found on every other plate on the ab- 

 actinal side. The small spines are club-shaped. The buccal membrane inside and outside the buccal 

 plates is richly provided with rather small, simple fenestrated plates, some of those outside the buccal 

 plates are complicate and carry pedicellarite. No spines on the buccal plates. The globiferous pedi- 

 cellarise (PI. XIX. Figs. 6, 12) are very characteristic. There is only one unpaired, very strong lateral 



1) Bidrag til Kundskab oni Echinideme. p. 27. 



15' 



