REPORT ON THE ECHINOIDEA. 53 



will show at once ; the verticillation also of Salenia hastigera is not produced as in the 

 Diadematidse, but by the regular arrangement of the processes of the outer sheath as in 

 the Cidaridse. 



There still remains also tlie other important feature, thus far found only among the 

 Cidaridse, the peculiar nature of the secondary spines forming, as in the Cidaridse proper, 

 the rows of papillae regularly arranged in the intertubercular spaces of both areas, and 

 forming also the secondary spines. The jaws and teeth of Salenia do not give as 

 definite information regarding the affinities of the genus. The teeth of Salenia hastigera 

 are, like those of the Echinidge proper, keeled, though with a broad flat keel, while the 

 compact nature of the pyramid with its small apical foramen, and the proportionally 

 large size of the tooth, brings them into close proximity to the Cidarides, between them 

 and the Axbaciadae; nor is the presence of gills and slight gill cuts an objection to their 

 association with the Cidaridse. 



I have already called attention, in the Ee-\asion, pp. 645 and 694, to the existence 

 of openings for the passage of giUs, and theii- protrusion through these openings 

 when alive, in our Florida species, although Mllller denies their existence. Mr Charles 

 Stuart (Trans. Lin. Soc, Dec. 1877) has given excellent figures of organs which are 

 undoubtedly gills placed within the imbricating membrane, but has not traced their 

 extension outwards. Whether it is these organs (gills) which find their way through 

 the cuts or not in our Florida species I am unable to state, and a renewed examin- 

 ation of living specimens will be necessary before we can settle this interesting 

 question. 



I am not the only writer on Echinids who has associated more closely than has usually 

 hitherto been done the Salenidas and Cidaridse. De Loriol had previously, in the Echinol. 

 helv., taken very much the same ground, though he subsequently modified his view, and 

 now inclines to unite the Salenidse to the Glyphostomes as a tribe, and not to the Cidaridse, 

 which he contrasts to the other regular Echinids as Holostomes. I do not feel that this 

 character taken by De Loriol can be employed to denote primary subdivisions among the 

 Echinoidea, for among the Diadematidaj and Echinothuridse we at once find forms, 

 otherwise closely allied, which differ radically in this one point considered so essential by 

 De Loriol, and as fast as new material accumulates both among living and fossil Cidaridse 

 it little by little shows the insufficiency of characters on which we have been accustomed 

 to contrast so strongly the Cidaridse with the other famihes of the regular Echinids. I 

 need only mention here the enormous difference made in our estimate of the value of the 

 famdy character of the Cidaridse by the discovery of such genera as Diplocidaris and 

 Tetracidaris. 



