ECHINOIDEA. II. 



The triphyllous pedicellarite are likewise ver>- similar to those of iiarrsiaiiKs. The same holds good 

 for the spines and for the spicules of the tube-feet. — A gas siz states (Panamic Deep-Sea Echini p. 124) 

 that in young C. Wyvillii the labnim is followed by two plates, the sternum being absent; this is, 

 evidently, due to a lapsus memorise. I need onh' refer to the figure 236 on p. 164 of the same work, 

 representing the plastron of a specimen 18""™ in length; it shows the plastron to be of the same struc- 

 ture as in Urechinus, as might be expected to be the case. 



Perhaps two species have also been confounded under the name of Cysfcchinus Wyvillii in 

 the Challenger -Report. A comparison of the figures 1—4 with figs. 5—8 of PI. XXIX, further of 

 PI. XXIX. a with PI. XXIX. b at any rate gives a strong impression that two distinct species are re- 

 presented here; moreover, the high form is so very like Cystcchi)nis Loveni that it must beforehand 

 seem much more reasonable to associate it with this species than with the low form of C. Wyvillii. 

 To be .sure, Agassiz points out (Panamic Deep-Sea Ech. p. 159) several features which distinguish 

 C. Lovf.ni from the high form of C. Wyvillii; but none of them seem to be of such value that it would 

 preclude regarding them as the same species. I have examined the pedicellariae of a specimen of the 

 high form (St. 147) and find them to agree with those of the low form of Wyvillii. On the other hand, 

 the pedicellariae of C. Loveni differ onh" little from those of Wyvillii ; I cannot therefore find herein 

 a definite proof that the high form is really the same species as the low form. Neither is it any proof 

 of their identitv that they occur together on the same locality. The question can only be decided 

 after a very careful examination. 



'Cystechinus:> (UrrchiniLs) Loveni (a specimen from the Albatross , St. 3415, examined in tlie 

 U. S. National Museum) differs only little from U. gigatitezis and IVyvillii \\\t\\ regard to the pedicellariae. 

 The globiferous pedicellarite are more like those of giganteus. though not so large; in the two speci- 

 mens I have found, there are two teeth on each side of the terminal opening of the blade. The tri- 

 dentate pedicellarite (PI. IX. Fig. ig) are upon the whole longer and more slender than in gigii)if<iis; 

 the edges of the basal part are generally more or less produced. Ophicephalous and triphyllous pedi- 

 cellariae as in giganteus. the latter, however, mostly a little more narrowed below the blade. Spines 

 and spicules do not present any characteristic specific features. 



The two species vesica and Rathbuni originally referred to Cyslechiniis have with full right been 

 transferred by A gas siz to a new genus, /*//c///(7/'^(;//m?« which is distinguished from the former f6^r^^///- 

 nusj by the small size of the plates adjoining the peristome and especially through the structure of 

 the plastron, the labrum being in contact with the two plates 5. a. 2 and b. 2, a very conspicuous dif- 

 ference from Urechinus (Cystecltinus) in which the plate S-b. 2' alone occupies the whole space at the 

 outer end of the labrum. The genus Pilematecluiiits would thus represent a uu)re ])rimitive form lliau 

 Urechinus. Another very peculiar feature of this genus is the \er\- thin and flexible test. 



IHlevtatechinus Rathbuni has been very carefully figured ami described by A gas siz (Panamic 

 Deep-Sea Ech. p. 165) as regards the structure of the test; the pedicellariic etc. are not mentioned. 

 Having examined specimens of this species («Albatross ; St. 3360) in the U. vS. National Museum I am 

 able to give some information thereof. The four usual kinds of pedicellarice were found. The glol:)i- 



' I quite iijjree with Lambert in his interpretation of thi.s jUate. (Conip. Laniljert: HtinKs inori)hologiques ,sur le 

 Plnstron ties Si)atan),'ules. Hull. Soc. Yonne. 1892.) 



