No. 4. — Preliminary Notice of a few Species of Echini, 

 by Alexander Agassiz. 



The following species are briefly noticed in advance of the fuller 

 descriptions of the Illustrated Catalogue to complete the synonymy of 

 the species of Echini in the collection of the Museum. 



Strongylocentrotrus armiger.* 



Test thin, flattened above, regularly arched below ; is at once distin- 

 guished from its congeners by its peculiar short, blunt, stout spines, 

 swollen in the middle of the shaft, resembling those of Echinometra 

 oblonga. The large primary tubercles, arranged in two principal verti- 

 cal rows, in both areas, flanked by indistinct vertical rows of secondaries, 

 are all placed nearer the abactinal pole on the depressed portion of the 

 test, decreasing rapidly in size towards the actinostome. Genital pores 

 large. Poriferous zone broad, pores arranged in arcs of from six to 

 seven pairs. 



Free Public Museum (Liverpool) ; Brit. Museum; Mus. Comp. Zool. 

 — Australia. 



Sphserechinus Australise. t 



The Museum has received at various times, from Mr. Henry Edvvards, 

 a sea-urchin intermediate between Psammechinus and Strongylocen- 

 trotrus, remarkable for the thickness of its test, its compact abactinal 

 system, the uniform size of the primary tubercles ; the secondary tuber- 

 cles closely packed and filling completely the whole space between the 

 primaries, both in the ambulacral and interambulacral areas. The test 

 is globular, resembling, in outline, somewhat Amblypneustes, has no am- 

 bitus, a very small actinostome, with short, sharp, narrow actinal cuts. 

 The poriferous zone divided by secondary tubercles into an inner verti- 

 cal row of pairs of pores far above one another, and an outer part with 

 pores arranged in from three to four pairs, all the pores deeply sunken 

 between the secondaries. Actinal membrane covered by large elliptical 



* The species included in this genus by Brandt are, S. chlorocentrotus = Echinus 

 Drbbachiensis Mull (teste Grube), and the specie* of section D of Blainville, including 

 K. lividus, parvituberculatus, .... ; in a different section lie places E. tuberculatus 

 Blainv. V 



t Cryptopora Australia 1 Michelin MS. Kcole des Mines, Paris. 



