214 HAWAIIAN AND OTHER PACIFIC ECHINI. 



subsequently Mr. Agassiz spelt the name Rhinobrissus and that spelling has 

 been used by other writers, except that Hamann in Bronn's Thier-reichs in 1904 

 introduced another change by putting a y instead of an i into the last syllable. 

 What was thus originally Rhynobrissus became gradually transformed into 

 Rhinobryssus. It is time therefore that the original spelling be restored. 

 Duncan, without any specimens at hand, proposed a genus Neopneustes for 

 the West Indian member of the genus. Though it is unwise, at present, to 

 approve of this, it is possible that with sufficient material, characters of generic 

 value might be discovered which would justify the use of the proposed name. 

 The characters which Duncan gives are not evident in the specimen at hand, 

 or at least have no significance. The study of the pedicellariae in this genus 

 has been tantalizing because globiferous pedicellariae, and ophicephalous pedi- 

 cellariae, occurred only in one specimen each and each of these forms is 

 remarkably characteristic. There are few genera of Echini in which addi- 

 tional material for study is more urgently needed. 



Key to the Species of Rhynobrissus. 



Test highest posterior to apical system and sloping thence to anterior margin. 



Ambitus rounded pentangular; subanal plastron projecting backward beyond 



periproct pyramidalls. 



Ambitus ellipsoidal; subanal plastron projecting downward but not backward 

 beyond periproct. 



Paired ambulacra markedly petaloid dorsally ■placopetalus. 



Paired ambulacra not at all petaloid dorsally micrasteroides. 



Test highest at apical system near anterior end but posterior end about as high; ambi- 

 tus ellipsoidal; subanal plastron somewhat projecting posteriorly hemiasteroides. 



Rhynobrissus pyramidalis. 



A. Agassiz, 1872. Bull. M. C. Z., 3, p. 58. 



Plate 146, figs. 28, 29. 



In addition to the holotype from the China Sea, figured in the Revision, 

 there is in the M. C. Z. collection a small spatangoid purchased of Salmin ami 

 said to be from Siam, which seems to be the young of this species. On this 

 small specimen there are many ophicephalous pedicellariae about the subanal 

 fasciole and these have a very characteristic form. The valves PI. 146, fig. 

 28) are .20-.30 mm. in length with the conspicuous loops (PI. 14f>. fig. 99) .04 

 .07 mm. more. Besides these ophicephalous pedicellariae, I found only one 



