l68 ECHINOIDEA. II. 



Confluent posterior petals are found in Brissopsis luzonica, atlantica, elongata, Oldhami and Toxobrissns 



pacificus. 

 Divergent — - — - lyrifera, alta, columbaris and n. sp.' 



5 ambulacral plates are included in the subanal fasciole in Brissopsis luzonica, Oldhami, elongata, n. sp. 



and T. pacificiis. 

 4 — - — -- — - — lyrifera, alta, columbaris and at- 



lantica. 

 The first ambulacral plate reaching within the subanal fasciole the 7th: Brissopsis elongata, n. sp. and 



T. pacificus. 

 — — — — — — - - 6th: lyrifera, alta, atlan- 



tica, luzonica, Oldhami, columbaris. 

 The labrum ends off the 1st adjoining ambulacral plates: Br. lyrifera, alta, atlantica, luzonica, Oldhami. 



columbaris and ;/. sp. 

 — — - - 2nd — : - elongata and T. pacificus. 



Globiferous pedicellarise with the valves ending in two long hooks: Br. lyrifera and luzonica. 



— several short teeth surrounding the terminal opening: Br. alta. 

 of two kinds, one with long and slender valves, ending in two long hooks, 

 the other with short valves with several teeth round the terminal 

 opening: Br. atlantica. columbaris (?only the slender form known), elon- 

 gata (? only the slender form known). 

 — — unknown : T. pacificus, Br. Oldhami and n. sp. 



From this summary it is evident that none of the characters give the same grouping of the 

 species; there is such a mingling of all the characters that it seems quite hopeless to distinguish 

 different genera among them. If different genera be maintained, they can only be characterised by 

 one of the characters named above. In that case it would perhaps be the most natural thing to take 

 the confluent ambulacra as the distinguishing character; but then the name Klein ia Gray would have 

 the priority and would have to be revived instead of Toxobrissns — the more so as the name Toxo- 

 brissns can in no case become more than a synonym of Brissopsis, as Lambert informs me in a 

 letter. I, for my part, find it preferable to keep all the recent species in one genus, Brissopsis, instead 

 of dividing them in a rather artificial way into two (or more) genera. 



1 The species mentioned above p. 163. The Brissopsis circcsemita described by Agassiz and Clark in their 

 recently published < Preliminary Report on the Echini collected, in 1902, among the Hawaiian Islands- (Bull. Mus. Comp. 

 Zool. L. 1907. p. 257) has confluent petals like those of luzonica and only three ambulacral plates included by the subanal 

 fasciole. The numero of the first plate reaching within the fasciole is unknown. The labrum is only staled to be nearly 

 straight; the pedicellariae are unknown. 



