ECHINOIDEA. II. 21 



cellariæ; they are certainly veiy peculiar, bnt may be enibryoiiic conditions of unknown pedicellariæ 

 similar to tliose he figures for Pli.placenta. As for his remarks on Phonnosoiiia tcnuc, I would suggest 

 to Dr. Mortensen that the Report on the Challenger -Echini was issned in 1881, and that his menioir 

 was pnblished in 1903; he can scarcely expect genera proposed in 1903 to have received any recogni- 

 tion in 1881 . 



It is possible that the genus Hapalosonia (not Hoplosoii/a) cannot be maintained, in which case 

 the onl}- species, pclluciditin. would have to be referred to the genus Aræosomn, since its pecuhar glo- 

 biferous pedicellariæ are evidenth- only a special developnient of the tetradactylouss pedicellariæ of 

 the latter genus, as shown by Dr. de Meijere. That they are not embryonic conditions of unknown 

 pedicellariæ is certain; otherwise, fully developed forms would also have been found among the not 

 very few specimens seen b>- me, and Dr. de Meijere especially would have found them in tlie ver\- 

 rich material he has had for study. Whether now the genus Hapalosonia has to be nuiintained (as I 

 think it has) or not, I certainh' did not den\- the close affinit}' of A. prlbtciduin with A. coriaceuiii 

 and tcssclatuni because I suggested a separate genus for the former, but, on the contrary, 1 suggested 

 a new genus for it, because I found it too distantly related to A. coriacrum and tcssrlatum to refer 

 it to the same genus witli these species. The use of the word because ir, this place is thus not quite 

 fair, and the same holds good in other instances, thus for example wheu it is said on the same page 

 as the above: I have nothing to say regarding Dr. Mortensen's sneers at descriptions of pedicellariæ, 

 because the\ do not fit with his classification?. My criticism of the description of the pedicellariæ of 

 Phonuosoma fcinir (as well as of other species) given by Professor Agassiz is certainly sufficientlv 

 justified by the character of that description, as will be agreed, I imagine, by anybody who will take 

 the trouble to read my remarks on that subject (Part I. p. 57). 



That Professor Agassiz could not in 1881 recognize the genera projjosed by me in 1903 is 

 self-evident. But, nevertheless, I tliink the remark to which Agassiz refers here quite justified 

 (Parti. p. 55). After quoting from the Challenger -Echini p. 87 as follows : In the only species of 

 the group of which the Challenger collected a complete series (Phoruiosoiiia tciiur) there was little 

 difficulty in recoguizing the young as belonging to the adult I continue: We could scarcely wish 

 to find a more pregnant proof of the difficult}- or impossibility of determiuing Echinids without taking 

 the pedicellariæ into con.sideration . . . With regard to the excellent long series of .Phormosoma, tcnue, 

 there are among the .specimens referred to this species by Agassiz at all events two different genera, 

 but no genuine Phori/iosoma.h, Professor Agassiz has now established a new species of the genus 

 Kamptosoiiia, K. indistiiictuiii A. Ag., on a specimen from the Challenger St. 272, referred to Phor- 

 uiosoiiia tcmie (p. 110). I venture to imagine that a more careful examination might have made it 

 possible to recognize this specimen as belonging to a separate genus already even in 1881 ; of course, 

 it would at that time have been impossible to know the name to be proposed b}- me later on, but 

 the genus realh- did exist already at that time. It is also worth noticing that this genus is sufficiently 

 characterized by its peculiar ambulacral structure alone, without regarding the pedicellariæ and spines. 



Professor Agassiz does not deny himself the pleasure of correcting me w^hen mentioning 

 ■iPhormosomay, asterias as »the last of the Echinothurids described from the «Challenger. (p. 86); lam 

 sorry to have to call his attention to the faet that, since I had already treated all the other species, 



