j-Q ECHINOIDEA. I. 



Colobocentrotus Brandt (emend.). 



Pores nuiltigeminate; primary tubercle on all the ambulacral plates. The pore areas on the 

 actinal side petaloid. The buccal membrane with numerous fenestrated plates, partly hidden in 

 the skin. Spines both on the buccal plates, and on some of the plates outside of these. The test 

 oblong, flat. The spines very short, thick, truncate, form a dense mosaic on the abactinal side. The 

 spines on the ambitus longer, flat; those on the actinal side of the common form. 



Species: C. atratns (L.), Mcrtcnsii Brandt. 



Distribution: The Indo-Pacific Ocean. Littoral forms. 

 Incerta sedis: 



Ecliiiuis Diiilticolor Yoshiwara. 



Toxopiicustes ii/nciilnfus (Lamk.). 



Strongylocfutrotus nicxicanus (Ag.). 



— imdus (Ag.). 



— globiilosus (Ag.). 



The svstem given here is, I think, in all essentials an expression of the natural relation of 

 these forms. To be sure, we must a priori hesitate before building up a s\stem chiefly on so minute 

 things as pedicellarise and spicules. But the result is the best possible one: no undoubtedly connected 

 forms are separated; on the other hand, forms hitherto placed ver\- far from each other in spite of their 

 great similarity as to habitus, are now put together {Pan-c/iiini.s and Loxcchiiius). That the boundary 

 line in one place is somewhat arbitrary is no important objection to the system — this will be the 

 fact everywhere, where transitional forms are found. The genus Pseudecliinus is here referred to the 

 Ecliinometridcc; but there can scarcely be an>- doubt that it is also closely allied to the Echiiiida-, it 

 seems especialhlo be a near relation of Sferechinus inagellaiiicus. Here it has been referred to the Ec/iino- 

 wrtridcr especially for practical reasons, it being then possible to gi\e a quite certain character of 

 these two families: in one teeth on either side of the blade of the globiferous pedicellariie , in the 

 other only (Uie unpaired lateral tooth. PscudccJiinus forms the connecting link between the two 

 families, and it is especially worthy of notice that in this genus may .sometimes be found an indication 

 of a lateral tooth also on the other .side of the blade of the glol)iferous pedicellarife. 



The family Toxopneusitda- is siiarply limited from the other two families, without transitional 

 forms. Objections can scarcely be raised against the subfamily Schizrc/iijiiiur — all the genera 

 referred thither, are evident!)- closely allied. I^ess sure are the subfamilies Parasalcnuuc and Sfrotigy- 

 locentrotince. Possibly the feature whether the globiferous pedicellarioe have a neck or not, is luit of 

 so great importance, as has here been supposed; but I think it impossible to decide this fact with 

 certainty, as long as only so few forms belonging here are known. 



That no other outer characters are found in these forms, which ma\- be used in the classifica- 

 tion, I think to be certain; both the test and the spines have been studied rather thoroughly, .so that 

 anything new of importance is scarcely to be expected here. It is hardlv probable that the inner 

 anatomical structure will \ield systematic characters of any greater importance, l)ut this question, at 



