42 TROPICAL PACIFIC ECHINI. 
in which teeth were observed, have no teeth or lantern * * * and nothing is 
left of them * * * so that in the older and adult stages of Echinonéus its 
relationship to the Spatangoids is in no way modified. * * + 
“Tt is interesting to note that this dentate stage of Echinonéus should 
connect the embryonic Spatangoids with the early stages of Clypeastroids and 
of the Echinoconide, while the toothed Pygastroides of Lovén connects it with 
some of the Echinoconide; both Echinonéus and Pygastroides are West Indian 
genera. 
“The presence or absence of auricles, teeth and pyramids forms the basis 
of Zittel’s classification of the irregular Echini into Gnathostomata and Atelo- 
stomata. The position of the anal system on the actinal surface close to the 
actinostome is a very modern feature: its gradual passage from an anal system 
enclosed within the calycinal system as in Pygaster, where it is outside of the 
abactinal system, can be traced towards the ambitus to the ambitus and finally 
to an actinal position. 
“In some of the Holectypide the jaws are greatly reduced in size and 
solidity and their importance much lessened, and in others the Jaws have entirely 
disappeared, the perignathic girdle having become rudimentary. In the Echino- 
metrade the auricular girdle is most highly developed. In the Holectypide 
we find primitive irregular Echini as well as types which have persisted to the 
present day. In the Discoidea and Galerites the ambulacral processes and 
teeth are absent; in the auricular girdle the processes become low. In the Cly- 
peastroids there are neither braces nor compass, the jaws move horizontally, 
and finally in the Atelostomata the girdle and jaws are completely absent. We 
may imagine the process of resorption of the lantern of Echinonéus to have gone 
through some such succession.” 
The specimens upon which Mr. Agassiz based the above remarks were 
collected by Dr. H. L. Clark who has kindly supplied the following notes:— 
~ Echinonéus occurs at Port Antonio, Jamaica, only in the sand-flat within 
the reef on the north and west sides of Litchfield Point. Search in similar 
habitats in the vicinity of Port Antonio, both in 1897 and in 1909, failed to 
reveal a single specimen. 
“On this sand-flat, which is more or less covered by a feeble growth of 
short eel-grass, are numerous fragments of coral-rock, ranging from a few inches 
to two or three feet in diameter. These fragments are more or less imbedded 
in the sand and it is under them that Echinonéus occurs, commonly in company 
with Brissus unicolor Klein. As a rule, both these species are completely buried 
