18 PANAMIC DEEP SEA ECHINI. 



the miliaries have been formed on the ocular plates of Dorocidaris pana- 

 mensis from the stage represented on PI. 3, fig. /, in the ocular of the odd 

 anterior ambulacrum of a specimen of 10 mm., Fig. 43, as they have increased 

 on the ocular plate of the same ambulacrum in a specimen ol 26 mm., 

 Fig. 14 (PI. •'!. fig. .'). to pass into the si ill more numerous miliaries 

 regularly arranged on the same ocular of a specimen of 30 mm., Fig. 4"> 

 (PI. 3, fig. J); additional miliaries being constantly added between the 

 older miliaries and I he ocular pore, and in I he following rows on the 

 sides of the first-formed miliaries. 



In the Cidaridae, according to Dr. Mortensen, the small pedicellarise 

 "are highly similar in almost all species, hut they may vary very much 

 in the separate individuals. The tridentate ones are belter, hut they 

 are also highly variable in the separate individuals. Most applicable for 

 the classification are the large globiferous pedicellarise." 



Doederlein, basing his conclusions on his careful researches regarding: 

 the Cidaridse, states that in that family the pedicellarise offer no characters 

 to distinguish natural groups within the family, and that xcvy closely 

 allied forms of pedicellarise are found in species only distantly related. 

 Dr. Mortensen comes to a radically opposite conclusion, and suggests that 

 species having the same kind of pedicellarise proves them to be nearly 

 related ; so that Cidaris metularia and Cidaris verticillata should be united in 

 one genus, — two species which are more readily distinguished by the 

 characters of the spines and tests than any other species of the family. 

 Dr. Mortensen also adds Cidaris baeulosa to the same genus. I have never 

 seen any specimens of this species the spines of which show the arrange- 

 ment of the thorns recalling that of C. verticillata. 



M. de Meijere has adopted the infinitesimal classification of Dr. Mor- 

 tensen, and appears as its ardent supporter; and yet in spite of this 

 the new classifying tool does not seem to do its work properly in all 

 cases, as M. de Meijere returns to Duncan's classification of Cidaris, 1 and 

 rejects all the genera based on the structure of the pedicellarise proposed by 

 Dr. Mortensen, as well as all others hitherto proposed, for the very reasons 

 which have satisfied Dr. Mortensen of the correctness of his views. 



Dr. Mortensen harps on the fact that a great many species of Cidaris 

 as well as other Echinoids have been proved by him to belong to other 

 genera than those to which they were referred by others, and thus he 



1 "Siboga" Echinoidea, p. 204. 



