298 Dr. P. H. Carpenter on the 



1 Annals' had compelled the printing off of our communica- 

 tion in its uncorrected form. 



1. Page 219, six lines from bottom, for " each arm forms 

 the floor of a passage " read " each half forms the floor of a 

 passage." 



2. Page 241 : the last paragraph should commence as fol- 

 ] ows ; — " \ n the type species, G. Noricoodi, the central aperture 

 is closed by a group of small plates." 



This last error has been pointed out by Mr. Hambach * 

 in the following characteristic passage : " But not, as mis- 

 represented by Mr. Carpenter, is this cone-shaped integument 

 preserved on P. Norwoodi." 



In conclusion, I must beg of Mr. Hambach that if he 

 should wish to refer to my papers on any future occasion, he 

 will take a little more care than he has hitherto exercised to 

 retain the sense of the original, when he gives it in his own 

 words and not in mine. 



Some cases of this kind have been noticed already* but 

 there are two of a much more serious nature. 



On page 544 f Mr. Hambach quotes me as saying, " Mere 

 differences in the relative sizes of the calyx-plates are of very 

 little systematic value "J. Two pages further on, however, 

 he discusses the differences between the two groups of so- 

 called Pentremites, which are referred by Mr. Etheridge and 

 myself to Pentremites and to Schizoblastus respectively ; and he 

 says, " I see no good reason to separate the first division from 

 the second, because the number and relative position of these 

 plates to each other remains the same, and, as differences in 

 the size of the calyx plates (as Mr. Carpenter remarks) are 

 of no systematic value, they should not be separated." 



Is Mr. Hambach here referring to the passage which he 

 has quoted in full on page 544? If so, one of his two ver- 

 sions of it must be wrong, and it is not the first one ; and if 

 not, I will thank him to give me the exact reference to the 

 statement which he paraphrases on page 546. 



In Mr. Hambach's first paper § he gave the following de- 

 scription of the lancet-plate of Pentremites : — " Its anterior 

 side is smooth and slightly convex, whereas the posterior 

 is concave, semilunar, and grooved in its whole length 



for the reception of some duct or vessel In the 



majority of the species, or at least in the typical ones, as 

 Pentremites florealis, sulcatus, piriformis, etc., the width of 

 the lancet piece is half as great as that of the ambulacral 



* Trans. St. Louis Acad. vol. iv. p. 541. t Ibid. vol. iv. 



\ " Remarks upou the Structure and Classification of the Blastoidea," 

 Report of the York Meeting of the British Association, 1882, p. 635. 

 § Trans. St. Louis Acad. vol. iv. p. 149. 



