354 BRISSOPSIS LYKIFERA. 



though, judging from the analogy, there is nothing excepting the flatness of 

 the test which would be contrary to its being the young of either Agassizia 

 or Schizaster. 



The young Agassizia, 6.2'" m in length, is a flat elliptical Spatangoid (PI. 

 XIV. f. 9) resembling Gualteria. The peripetalous and lateral fascioles 

 have the same general limits as in the adult, hut the arrangement of the 

 pores in all the ambulacra is identical ( PI. XIV f. n); there is but a single 

 pore for each ambulacral plate, as it exists in the anterior pair and odd am- 

 bulacra of the adult; the ambulacral grooves are not yet formed, the anterior 

 groove alone being slightly indicated ; the mouth is very slightly labiate 

 (PI. XIV. f. 10, 12). 



(HEMIASTER.) Brissopsis. 



Brissopsis AGASS. 1840. Cat. Syst. Ectyp. 



Test thin, more or less ovoid ; the apex is nearly central, the odd anterior 

 ambulacrum but little prominent, ambulacral petals unequally developed. 

 Subanal fasciole and peripetalous fasciole entire. This genus does not seem 

 to be entitled to rank as more than a subgenus of Ilemiaster, where we have 

 a subanal fasciole; while ToxobrisiUS, which is said to have no subanal fasciole, 

 cannot, it seems to me, be separated from Ilemiaster simply on account of the 

 divergence of the ambulacra as proposed by Desor, a feature which is strictly 

 one of growth, and not one to be taken as a permanent character. Kleinia, 

 as based upon the original specimen (Kleinia luzonica) of Gray, certainly is 

 nothing but a Brissopsis, having a most distinct subanal fasciole. If the sub- 

 anal fasciole is really absent in Toxobrissus, it cannot, as Liitken considers it, 

 be identical with Kleinia. It may be that other characters will yet be traced 

 to separate it from Brissopsis ; if not, then Kleinia and Toxobrissus will both 

 become synonymous with Brissopsis. 



Brissopsis lyrifera 



! Brissus lyrifer Forbes, 1841. Brit. Starf. 



! BrissopxLi lyrifera A<;ass. 1847. C. R. Ann. Sc. Nat. 



Pi. XIX. f. i - g ; PI. XXI. f. 1-2. 



Test thin, ovoid, depressed; profile regularly arched, truncated posteriorly; 

 vertex posterior; peripetalous fasciole moderately broad, somewhat flexuous ; 

 posterior portion very distinct, less clearly defined towards anterior; all am- 



