130 



ECHINOIDEA. I. 



Ilia)- be distinguished by the pedicellarise ; after the material before me I must agree with Agassiz 

 that onh" two species can be distinguished: mamillahis and trigonarius. But then these two species 

 may immediately be recognized by their tridentate pedicellarise (besides by the characters stated by 

 Agassiz [Rev. p. 427 seq.l). The tridentate pedicellarias in Coloboc. atraftis are ver\- similar to those of 

 //. frigonarhis; the \-alves join through their whole length (PI. XIX. Fig. i); in C. Alcrfcns/i I have 

 not sticceeded in finding these pedicellarias. The ophicephalons and triphyllous pedicellarice of the 

 common form. The spicules are bihamate; in Hctcrocrntrotiis they are exceedingly numerous as well 

 in tube feet as pedicellarise, in Colobocentrofiis they are very few in nmnber. 



Of the forms referred to Triplechinidce^, we have still left Phyiiivsoma irontlarc Ag., Hcmi- 

 pedina ciibnisis Ag., and iiiirabilis Dod. None of these forms I have been able to examine, so that 

 their place must for the present remain undecided. We ma\', however, draw same conclusions from 

 the existing descriptions. Of Phyniosoma Agassiz figures valves of globiferous and tridentate pedicel- 

 larise (Rev. of Ech. PI. XXV. 4, 5) from which is seen that no lateral teeth are found on the globiferous 

 pedicellarise; whether a neck is found or not is not mentioned. The spicules are not known. A peculiar 

 feature is seen from the figures given by Agassiz (Rev. PI. \TI. a. f. 6, 8, 9), viz. that the pores form 

 arcs with alternately two and three pairs. As the figures cited are photographs, there can be no 

 doubt of tlieir correctness, although Agassiz, as far as I can see, does not mention this fact. Tliis 

 peculiar feature together with the crenulate tubercles renders it undoubtful tliat this form has 

 nothing to do with the genuine Kchinids. Pomel (324) puts it down as the only recent representative 

 of Les Phymosomiens , and readopts the name of Glyptocidaris^ by wliich it was originally described 

 by Agassiz. I shall express no opinion whether it really is to be classed with Les Phymosomiens*, 

 partly because my knowledge of these fossil forms is too small, partly because upon the whole I am 

 rather sceptical with regard to the possibility of referring with certainty the recent forms to the fossil 

 ones. Accordingly I agree with Pomel that the name of Glyptocidaris must be readopted for tliis 

 form, as the name of P/iymoso/iia has originally been used of fossil forms. 



Of JIniiiprdiiia cuhoisis Ag. are figured (Rev. of Ech. PI. III. f. 6 — 7) a tridentate pedicellaria 

 and a smaller one which is stated to be a young tridentate pedicellaria, but which is rather a globi- 

 ferous or ophicephalons one; neither is given with sufficient details. The spicules are not known. 

 The perforated tubercles show, however, that this form lias nothing to do at all witli the other Tn'pl- 

 echinida!>. Agassiz says himself that it is a Pseudodiadematid, but to refer all Psrudodiddriuatida- to 

 7yil^lcchinid(z> is by no means admissible, so nnicli the less as these Triplechinidcr > prove to l:)c so 

 heterogeneous that the genera referred thither must be distributed to three different families. Pomel 

 (324) refers it to Les Pediniens> as the onh- recent representative, and he readopts tlic name of 

 Canopediiia liy which Agassiz has originally described it With regard to the name I must agree 

 with Pomel for the same reasons as stated above under Glyptocidaris crenulnris. I shall not contest 

 tliat the referring to Les Pediniens* is correct, but I must regard it as certain that it has nothing to 

 do with - Triplcchinidoiy-:. 



Having thus given a natural grouping of the s])ecies I sliall liave to treat tlie question of tlie 

 grouping of llie numerous genera. Tliat the systems mentioned abo\e, wliich are cliiefh- based on 

 tlie number of the pairs of pores, give no impression of tlie real relation of llie forms need not to be 



