REPORT ON THE ECHINOIDEA. 51 



The Salenia tertiaria of Tate ^ is carefully described by Duncan.^ He mentions the 

 numerous ambulacral tubercles in four vertical rows somewhat as in Salenia hastigera, 

 and more especially the presence of but a single pair of pores to each tubercle as in the 

 recent SalenidsB, while this is not the case in the older fossil Salenid« ; and it is somewhat 

 remarkable to find this structural feature in the Tertiary species, for, from what we know 

 of the mode of development of the ambulacral regions in other Echinids, the character 

 just alluded to in the older Salenidse is not an embryonic one, as the crowding of the 

 poriferous zone is, as far as we know, now prominently developed only in the older stages 

 of growth of the Desmosticha. The Hemicidaris character of the existence of a few 

 large primary tubercles near the actinostome is quite striking in Salenia varispina, and 

 much less so, though it exists, in Salenia hastigera. 



Duncan has described in the Annals and Magazine, vol. xx. p. 70, the spha^ridia of a 

 species of Salenia, dredged by the Challenger, which he names Salenia prof undi ; and on the 

 strength of the presence of sphaeridia and their absence in the Cidaridae, as well as the 

 character of the buccal membrane, he retains the Salenidee as an independent family, and 

 as more closely allied to the Echinidae proper than the Cidaridse, with which I had 

 associated them more closely than other authors had done. I, however, hardly think that 

 the single additional structural point he mentions (the existence of sphseridia) is a 

 sufficient ground for taking what I consider a retrograde step in our ideas of the affinities 

 of the Saleuidse. 



An unfortunate misprint occurs in my description (Eevis. Echini) of Salenia 

 varispina. While speaking of the imbricating buccal membrane, it reads " much as in 

 Echinocidaris ;" it should have been " as in Trigonocidaris." I may be allowed to state 

 that I was fuUy aware that Echinocidaris is identical with Arhacia, as Dr Duncan states 

 (see Ann. and Mag. Nat. Hist., 1877, vol. xx. p. 248), and also that the imbricated plates 

 of Salenia varispina show on my figures (Eevis. Echini, pi. iii.) ; and as I have shown, this 

 is an important difierence between Salenia hastigera and Salenia varisjnna. 



As Duncan justly remarks with regard to the number of the primary tubercles, their 

 number cannot be limited to ten as I had stated it in the Revision; but, on the other hand, his 

 statement that the number of primary tubercles is indicated long before the test assumes its 

 largest size, will have to be greatly modified judging from the young SalenitB dredged l^y the 

 " Blake." To this point, however, and to the relationship of Salenia varispina to Peltastes or 

 Hyposalenia, I shall return in the final Report of the Blake Echinoidea, when giving an 

 account of the changes undergone by Salenia during growth, which afiects materially the 

 position of the anal system. I should say, however, that the single specimen of Salenia on 

 which my original description in the Revision was based appears to be somewhat anomalous 

 in the size of the anal system, and its degree of encroachment on the genital plates. I do 



1 Tate, Quart. .Jour. Geol. Soc. London, vol. xxxiii. p. 256, fig. 2, p. 257. 

 - Duncan, Ami. and Mag. 1878, vol. ii. p. 61. 



